2016 Postgraduate Research Symposium Abstracts booklet · 2016-09-30 · 2016 Postgraduate Research...

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2016 Postgraduate Research Symposium Abstracts booklet School of Physics and Astronomy, University of Leeds 5th of October 2016

Transcript of 2016 Postgraduate Research Symposium Abstracts booklet · 2016-09-30 · 2016 Postgraduate Research...

Page 1: 2016 Postgraduate Research Symposium Abstracts booklet · 2016-09-30 · 2016 Postgraduate Research Symposium Abstracts booklet School of Physics and Astronomy, University of Leeds

2016 Postgraduate Research SymposiumAbstracts booklet

School of Physics and Astronomy, University of Leeds

5th of October 2016

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Contents

Talk abstracts 1Tuning the Dzyaloshinskii-Moriya interaction via interface engineering in

epitaxial Co/Pt (Adam Wells) . . . . . . . . . . . . . . . . . . . . . . 1Fluctuating Finite Element Analysis - Development and Applications to

Cytoplasmic Dynein (Ben Hanson) . . . . . . . . . . . . . . . . . . . 2Near-infrared spectroscopy of Massive Young Stellar Objects (Robert Po-

mohaci) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2The Hall Effect in YIG/Pt bilayers (Amy Westerman) . . . . . . . . . . . 3Quantum Key Distribution: Will it Work in Satellites? (Freya Wilson) . . 3Hydrophobic drug delivery and why you should like microbubbles (Victoria

Mico) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Investigating ionised jets towards massive young stellar objects (Simon

Purser) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Magnetic properties of nanometre thick sputtered Yttrium iron garnet films

(Arpita Mitra) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Big Atoms for Big Science (Diego Quinones) . . . . . . . . . . . . . . . . . 5Influence of anion size on cellulose solution structure in imidazolium-based

ionic liquids (Stephen Green) . . . . . . . . . . . . . . . . . . . . . . 5Thermal effects in lateral spin valves (Georgious Stefanou) . . . . . . . . . 6Chemical tracers of a gravitationally unstable protosolar-like disc (Marc

Evans) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Quantum-enhanced metrology with the single-mode coherent states of an

optical cavity inside a quantum feedback loop (Lewis Clark) . . . . . 7New Approaches to Green Cellulose Processing (Wafa Ezzawam) . . . . . 8Helical magnetic structure in Fe(1-x)Co(x)Ge epilayers (Charles Spencer) . 8

Poster abstracts 11Towards the fabrication of high frequency lateral spin valves (Nicolas Peters) 11Properties of the CORNISH UCHII sample (Ivayla Kalcheva) . . . . . . . 11Scanning TEM-based spectroscopy observations of individual CuInS2 Qdots

(Andrew Harvie) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Rheology and relaxation dynamics in a chain-length series of methacrylates

ranging from oligomer to entangled polymer (Matthew Reynolds) . . . 12The metamagnetic transition in NiAl-buffered FeRh films (Jamie Massey) 12Why do Lipid Domains Register? (James Goodchild) . . . . . . . . . . . . 13Radio Properties of the CORNISH Planetary Nebulae (Tonye Irabor) . . . 13

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Microfluidic device fabrication for the imaging of Caenorhabditis elegansin a dorsoventral aspect for the study of its sensory neurons (JinyangChung) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Simple fabrication of scalable Liquid Crystal Elastomers with low glasstransition temperatures (Devesh Mistry) . . . . . . . . . . . . . . . . 14

Central Broadcast Quantum Cryptography (Beth Newton) . . . . . . . . . 15Spin ordering at the interface between diamagnetic Cu/amorphous Carbon

(Shoug Alghamdi) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Developing the use of microuidics for the detection of single molecules of

biomarker and single cell analysis (Liam Hunter) . . . . . . . . . . . 16Interaction of astrophysical flows with clouds and filaments (Kathryn Gold-

smith) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Voltage control of molecular spin ordering as probed by low energy muon

spin rotation. (Matthew Rogers) . . . . . . . . . . . . . . . . . . . . . 17Investigating Cold Shock Protein Interactions with single stranded DNA

using Single Molecule Force Spectroscopy (Ellen Kendrick) . . . . . . 17Tracking of Particles at Defects in Nematic Liquid Crystals (Anne Helen

Macaskill) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

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Talk abstracts

Tuning the Dzyaloshinskii-Moriya interaction via interfaceengineering in epitaxial Co/Pt 10:05 am

Adam Wells

Condensed Matter

In this presentation, we demonstrate control of the interface quality in epitaxial sam-ples of Pt(30A) Co(7A) Pt(10A) through variation of the deposition temperature ofthe Co and top Pt layers, and determine the effect on the Dzyaloshinskii-Moriya in-teraction (DMI). Using X-ray reflectometry, we find that the roughness-intermixingpeaks with deposition temperature at 250o C before rising rapidly after 400oC. Theseinterfacial changes before the rapid rise, however, leave the anisotropy unaffected.The net Dzyaloshinskii-Moriya Interaction (DMI) in these samples was found us-ing wide-field Kerr microscopy with applied in-plane and out-of-plane fields.[1,2] Itvaries with the relative quality of the top and bottom Co interfaces [2,3], up to aneffective field strength of 270 Oe, and even to change sign as shown in figure 1. Alower growth base pressure enhances these fields. DMI strengths were found in therange of -0.04 to 0.11 mJ/m2. In conclusion, the Co/Pt interfaces are exquisitelysensitive to the deposition temperature which, for low sputtering base pressures,gives rise to a method of tuning the DMI.References1. Je S.-G. et al., PRB 88, 214401, (2013)2. Hrabec A. et al., PRB 90, 020402(R), (2014)3. Lavrijsen R. et al., PRB 91, 104414, (2015)

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Fluctuating Finite Element Analysis - Development andApplications to Cytoplasmic Dynein10:20 am

Ben Hanson

Soft Matter

Biology is an inherently multi-scale process, with both intra and intermolecular localinteractions at the atomistic scale affecting the dynamics of the molecules over muchlonger length and timescales. This ’molecular sociology’ within the cell is of vitalimportance to the function of each individual molecule[1], yet very few techniquescurrently exist which are able to efficiently simulate dynamics at the mesoscale (≈5-100nm). To understand how these molecules function, more sophiscated modelsare needed. We present Fluctuating Finite Element Analysis (FFEA), a continuummechanical representation of globular macromolecules that can calculate dynamicaltrajectories from low resolution structural information such as electron density mapsor SAXS data[2]. We present a variety of simulations of geometrically simple objects,such as spheres and cuboids, to show the functionality and capabilities of FFEA.We also present a number of simulations of Cytoplasmic Dynein, a bipedal motorprotein, to show that FFEA allows insights into biological processes beyond thescope of currently available simulation techniques.References1. Robinson, C.V., Sali, A. and Baumeister, W. (2007), The molecular sociology ofthe cell. Science, 351(6276), 969-722. Oliver, R.C., Read, D.J., Harlen, O.G. and Harris, S.A. (2013), A stochasticfinite element model for the dynamics of globular macromolecules. J. Comp. Biol.,239, 147-65

Near-infrared spectroscopy of Massive Young StellarObjects10:40 am

Robert Pomohaci

Astrophysics

We present medium-resolution (R 7000) NIR echelle spectroscopic data for 38MYSOs selected from the Red MSX Source (RMS) survey. This is the largest sampleat this resolution at these wavelengths of MYSOs to date. We study several wind,disc and shock tracers. Photospheric absorption lines are visible in one object,allowing for the first time a direct estimation of the spectral type of an MYSO.The best fit is that of an early A supergiant, which can be understood throughswelling up caused by fast accretion, agreeing with simulations of (Hosokawa &Omukai, 2010). Mass accretion rates from Brackett gamma agree with results forlow and intermediate-mass YSOs, providing support for the idea that high-mass starformation is a scaled up version of the low-mass case. Finally, we obtain clues aboutthe wind emission geometry through studying velocity-resolved HI line ratios.

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The Hall Effect in YIG/Pt bilayers 10:55 am

Amy Westerman

Condensed Matter

The magnetic insulator yttrium iron garnet (YIG) has attracted a lot of interestrecently due to its potential applications in spintronic devices. When a metal witha high spin-orbit interaction (e.g. Pt) is deposited on top of YIG, effects such as thespin Hall magnetoresistance and spin Seebeck effect can be observed. An unusualHall effect has also been observed in these systems which has not been sufficientlyexplained in the literature. We have performed a detailed study of many differenttypes of magnetic interfaces with Pt, including using an interfacial dopant layer ofFe on a non-magnetic substrate, and have shown that this effect is interfacial inorigin. We have systematically increased the concentration of interfacial magneticion sites and show that the size and even sign of the Hall effect can be engineeredin both FePt and YIG/Pt systems.

Quantum Key Distribution: Will it Work in Satellites? 11:40 am

Freya Wilson

Experimental Quantum Information

Quantum cryptography is a method of keeping communications secure against anomniscient eavesdropper performing both quantum and classical attacks. There hasbeen some success with implementations particularly using optics. However to datethere is no successful implementation in microwave communications. We investigatewhether secrecy can be retained when using existing quantum key distribution pro-tocols in satellite communication and explore methods of integration with traditionalsatellite communication protocols.

Hydrophobic drug delivery and why you should likemicrobubbles 11:55 am

Victoria Mico

Molecular and Nanoscale Physics

Lipid coated microbubbles (MBs) have proven to be reliable vehicles for drug deliv-ery. Their ultrasound properties (US) provide them with the ability to retain drugsuntil a destruction pulse is applied, therefore allowing for spatial and temporal con-trol over drug release. Conveniently, these US properties can simultaneously be usedfor diagnostic purposes, turning MBs loaded with drugs into theranostic agents. Im-provements made towards the production of therapeutic MBs makes them attractive,inexpensive candidates for the delivery of drugs. Notably, there are a high percent-age of new pharmaceuticals that are hydrophobic, which leads to problems whendelivering them in vivo. Given that a number of these drugs have shown promising

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results against malignancies in vitro, there is an urgency to develop robust meth-ods to deliver them in vivo. We have developed hybrid MB-LONDs composites forhydrophobic drug delivery. LONDs are attolitre oil volumes capable of storing hy-drophobic drug molecules and protecting them from the aqueous environment of thebody, thus maintaining drug functionality and reducing aggregation. MB-LONDsarchitectures retain the ultrasound properties of the MBs, but also incorporate thedrug delivery benefits of the LONDs. MB-LONDs are assembled in a microfluidicdevice in a two-step process.

Investigating ionised jets towards massive young stellarobjects12:15 am

Simon Purser

Astrophysics

Massive star formation (forming stars larger than 8 solar masses) is a topic whichis relatively little understood. Forming massive stars (massive young stellar objectsor MYSOs) produce large radiative fluxes which tend to disrupt any dust and gasfalling towards them, halting their formation. One way around this is formationutilising an ‘accretion disc’ which reduces the cross-sectional area of the in-fallingmaterial exposed to radiative forces from the protostar. A consequence of these discsare ‘jets’ of ionised material which are ejected perpendicular to them at velocities inexcess of 500 km/s. Although direct observations of both disc and jet are common inlow mass systems, actual observational examples of both accretion discs and ionisedjets around MYSOs are much rarer. This talk focusses on a published work whichestablished these phenomena to be common features of massive star formation bythe radio detection of a statistically-sized sample of ionised jets. After a generaloutline of the field of research, I shall talk about how this sample was selected,observed, analysed and what we can infer from it about massive star formation ingeneral. I shall then conclude the presentation with a discussion about future workand also the open questions remaining in relation to ionised jets.

Magnetic properties of nanometre thick sputtered Yttriumiron garnet films12:30 am

Arpita Mitra

Condensed Matter

Generation of spin currents in magnetic insulators by spin pumping and spin Seebeckeffect has led to dramatic advances in spin currents research and its applications forinsulator based spintronics devices. Here we report the deposition of high qual-ity nm-thick yittrium iron garnet (YIG) film on gadolinium gallium garnet (GGG)by RF magnetron sputtering. The morphology and magnetic properties of the filmswere studied by using atomic force microscopy (AFM) and SQUIDVSM respectively.

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10-60 nm thick films have surface roughness of 1-3A, and (111) orientation.Our re-sults show that magnetic properties of YIG depend strongly on thickness: magneticmoment has linear dependence at room temperature. The saturation magnetizationand coercive field observed in thick films are 136 emu/cc and 0.50 Oe, respectively.FMR results showed narrow FMR linewidth and small damping (2.0 ± 0.6) × 10-4.Temperature dependence of magnetization of nm-thick YIG films has revealed aninteresting result, which can be attributed to an additional magnetic phase formingat the YIG/GGG interface due to the diffusion of Gadolinium during annealing.We have also studied the thickness dependence of the Gilbert damping parameterin nm-thick YIG film. Detail investigation of the properties of will make YIG filmsan ideal magnetic insulator for spintronics devices.

Big Atoms for Big Science 14:15 am

Diego Quinones

Theoretical Physics

We developed a new model of decoherence in atoms by low-energy interactions. Ourargument is that collisions of particles with the nucleus will alter the state of theatom by rapidly shifting the position of the nucleus, which will be perceived by theelectron as a sudden change in the electromagnetic potential. By measuring thetransformation in the atomic state, we can obtain information about the propertiesof the particles. This can be used to detect and characterize exotic particles, likethe ones that may constitute Dark Matter. The results showed that the effect ismore prominent, and therefore easier to measure, in highly excited states (Rydbergatoms), which present very big distance between the nucleus and the valence elec-tron. We extended our analysis to gravitational interactions, obtaining a model ofdetection of gravitational waves with atomic spectroscopy.

Influence of anion size on cellulose solution structure inimidazolium-based ionic liquids 14:30 am

Stephen Green

Soft Matter Physics

Ionic liquids are powerful solvents for cellulose dissolution, particularly those basedon the imidazolium cation. They have generated much interest for use in creatingcellulosic films, fibres and aerogels. In previous studies, cellulose, cellobiose andglucose solutions in 1-ethyl-3-methylimidazolium acetate were studied using NMRspectroscopy, diffusion and rheology. We have extended this work to 1-ethyl-3-methylimidazolium octanoate, in order to investigate the effects of a different an-ion chain length. The 1-ethyl-3-methylimidazolium octanoate systems were exam-ined over a range of carbohydrate (glucose, cellobiose and cellulose) concentrations(0% - 15% by weight) and a range of temperatures (20oC to 60oC). In 1-ethyl-3-methylimidazolium acetate, the decrease in self-diffusion coefficient is proportional

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to the number of hydroxyl groups per anhydrous glucose unit of the carbohydrate (3for cellulose, 4 for cellobiose, 5 for glucose). However, 1-ethyl-3-methylimidazoliumoctanoate does not follow this rule. This reveals a different structuring of 1-ethyl-3-methylimidazolium octanoate in relation to the dissolved cellulose. More recently,our work focusses on using conductivity measurements and studying other ionicliquids to further investigate the effect of changing architecture on ionic liquid prop-erties.

Thermal effects in lateral spin valves14:50 am

Georgious Stefanou

Condensed Matter Physics

Our devices are fabricated in the clean-room using a combination of electron beamevaporation through a shadow mask defined by electron beam lithography in aPMMA/MMA resist and conventional optical lithography and lift-off techniques.The use of a 3-axes sample rotation stage coupled with a base pressure 10−10 mbarpermits a flexible device design whilst retaining very clean interfaces between theSilver (Ag) and Permalloy (Py) electrodes. Using the non-local geometry, one canseparate heat, charge and spin currents and thereby study the effect of these inde-pendently. Thermally generated spin currents are known as spin caloritronics andare intrinsically interesting. In lateral spin valves (LSVs) it is important to under-stand the origin of the signals generated to properly determine the magnitude ofthe various contributions. There are different thermal effects in the non-local spinvalve systems, such as Joule heating, Peltier heating/cooling and Seebeck effect atdifferent parts of the device. The baseline resistance that is related to the Seebeckeffect in the detector/normal metal junction - was firstly described by Garzon et alin 2005 where they observed the temperature dependent asymmetry in the non-localresistance signal for the different relative magnetisations of the injector and detec-tor. We have characterised our devices using standard DC electrical transport toextract the spin signal and heating effects, where not only is there a non-zero base-line resistance but its magnitude exceeds that of the spin signal at temperatureshigher than 180 K.

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Chemical tracers of a gravitationally unstableprotosolar-like disc 15:05 am

Marc Evans

Astrophysics

In the very early stages of star formation the surrounding disc is likely to be ofcomparable mass to the star. If this is the case then the disc can be gravitationallyunstable, which produces spiral density waves that drive shocks in the disc. Theseshocks can enhance the local temperature of the disc material which has a knock-oneffect on the chemical rates and therefore the abundances of some molecular species.I have investigated a simulation of a disc that could be analogous to our early SolarSystem and I will talk about the effects of gravitational instabilities on this disc’sshort-term chemical evolution, which include persistent changes in some species’abundances and potentially observable tracers of the spiral features.

Quantum-enhanced metrology with the single-modecoherent states of an optical cavity inside a quantum

feedback loop 15:50 am

Lewis Clark

Theoretical Physics

In this paper, we use the nonlinear generator of dynamics of the individual quantumtrajectories of an optical cavity inside an instantaneous quantum feedback loopto measure the phase shift between two pathways of light with a precision abovethe standard quantum limit. The feedback laser provides a reference frame andconstantly increases the dependence of the state of the resonator on the unknownphase. Since our quantum metrology scheme can be implemented with currenttechnology and does not require highly efficient single photon detectors, it shouldbe of practical interest until highly entangled many-photon states become morereadily available.

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New Approaches to Green Cellulose Processing16:05 am

Wafa Ezzawam

Soft Matter Physics

New Approaches to Green Cellulose Processing Cellulose is the most abundant natu-rally occurring biopolymer, found in plants, bacteria and fungi and is potentially anunlimited resource for the replacement of our dependence on fossil fuels. This workuses ionic liquids, designer green solvents, to dissolve and therefore process cellulosewith. We are looking at the interactions between plant polymers, such as xylanwith cellulose, with the aim to form biomimetic materials. A solution of celluloseand xylan in the ionic liquid 1-ethyl-3-methylimidazolium acetate [C2mim OAc] wasexamined using NMR spectroscopy, diffusion measurements and low field relaxom-etry at various temperatures (20oC-60oC). The low field spin-lattice and spin-spinrelaxation times were measured for cellulose and xylan solutions and across the tem-perature range 60oC-30oC. We observed that the dissolving mechanism of xylan inthe IL [C2mim OAc] is close to that for cellulose. The diffusion coefficient of the an-ion is preferentially more reduced by cellulose than by xylan. It is generally agreedthat the anion is more active in the dissolution of carbohydrates than the cation.The dissolution mechanism of cellulose and xylan in [C2mim OAc] can be exam-ined via the mobility of the ions. We proposed that the number of accessible OHgroups belonging to the carbohydrates are reduced at certain xylan-cellulose blendcompositions, showing that at these concentrations there are significant interactionsbetween the two biopolymers.

Helical magnetic structure in Fe(1-x)Co(x)Ge epilayers16:20 am

Charles Spencer

Condensed Matter Physics

Magnetic skyrmions can form in materials that lack inversion symmetry and thussupport a Dzyaloshinskii-Moriya interaction (DMI) [1, 2]. They are topologicallystable and can be moved via spin-transfer torque at low current densities [3], makingthem promising candidates for spintronics [4]. To realise skyrmion-based devices,thin films are required. We have studied epitaxial films of Fe(1-x)Co(x)Ge grownby MBE. Shibata et al. showed that in Mn(1-x)Fe(x)Ge, the skyrmion size (propor-tional to the helical wavelength) was found to vary, and at a critical compositiondiverge, corresponding to an inversion of the helix chirality [5]. Here we alter theCo content and use polarised neutron reflectometry (PNR) to obtain the magneticdepth profiles and investigate the helical magnetic structure of these epilayers.References:1. S. Mhlbauer et al., Skyrmion Lattice in a Chiral Magnet, Science 323, 915-919(2009).2. U.Roler, A. Bogdanov, C. Peiderer, Spontaneous skyrmion ground states in mag-netic metals, Nature 442, 797-801 (2006).3. F. Jonietz et al., Spin Transfer Torques in MnSi at Ultralow Current Densities,

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Science 330, 1648 (2010).4. A. Fert, V.Cros and J. Sampaio, Skyrmions on the track, Nature Nano. 8, 152(2013).5. K. Shibata et al., Towards control of the size and helicity of skyrmions in heli-magnetic alloys by spinorbit coupling, Nature Nano. 8,723728 (2013)

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Poster abstracts

Towards the fabrication of high frequency lateral spin valves 1

Nicolas Peters

Condensed Matter Physics

This work is concerned with the fabrication of lateral spin valves designed to work atTHz frequencies. This should enable the generation and measurement of picosecondpulses of pure spin current. These frequencies are above ferromagnetic resonance(1-20 GHz), and therefore the exchange and spin orbit effects should be accessible.The design and fabrication of these devices will be discussed as well as the basics ofpicosecond electrical pulse generation.

Properties of the CORNISH UCHII sample 2

Ivayla Kalcheva

Astrophysics

The CORNISH VLA survey provides a complete and unbiased high-resolution sam-ple of 240 ultra-compact HII (UCHII) regions at 5 GHz. Counterparts were identifiedin the latest data of the Galactic plane - from infrared to X-ray wavelengths. Theaim of studying this sample is to shed more light on questions such as the feedbackprocess in high mass star formation regions and the Milky Way structure traced bythem, the evolution of H II regions and their eect on their environment. The posterwill report results on properties such as the physical sizes, Lyman fluxes, spreadof Galactic latitudes relative to the mid-plane and spectral indices to confirm theUCHII region identity. Early results from fitting X-ray spectral data are consistentwith massive star forming regions associated with hard diffuse emission and hint atchanges in the X-ray emission with evolution when compared to earlier and laterphases. Another important aspect that is explored is the morphology of UCHIIregions.

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Scanning TEM-based spectroscopy observations ofindividual CuInS2 Qdots3

Andrew Harvie

Molecular and Nanoscale Physics

The broad photoluminescence in chalcopyrite CuInS2 quantum dots (Qdots) hasbeen assigned to an InCu defect-to-valence band transition. However, the natureof this defect state within the Qdot is not understood. Here, scanning TEM-basedelectron energy-loss spectroscopy (STEM-EELS) was used to observe defect-richcompositional domains within individual CuInS2 Qdots.

Rheology and relaxation dynamics in a chain-length series ofmethacrylates ranging from oligomer to entangled polymer4

Matthew Reynolds

Soft Matter Physics

Glassy polymers are commonly used in a wide variety of industrial applications.Both their macroscopic and microscopic behaviours are often strongly affected byprocessing history, and the link between rheology and relaxation behaviour is im-portant and often complex. This presentation will outline recent work to determinethe variation of the rheological response and relaxation dynamics of a molecularweight series of oligo and poly(methyl methacrylates). Rheology data covering awide temperature range will be presented alongside results from broadband dielectricrelaxation spectroscopy and modulated and standard differential scanning calorime-try. The results will be presented in the context of recent models and behaviourpreviously reported for other polymer systems in the literature.

The metamagnetic transition in NiAl-buffered FeRh films5

Jamie Massey

Condensed Matter Physics

B2-ordered FeRh undergoes an unusual antiferromagnetic-ferromagnetic first orderphase transition on warming through a bulk transition temperature of order 380 K[1]. This change in magnetic state is accompanied by a lattice expansion [2], and amarked change in transport properties [3], indicating coupled magnetic, structuraland electronic elements. Here we report the growth of ordered FeRh on both GaAsand MgO. The NiAl buffer is used to stabilize the FeRh and reduce the latticemismatch [4]. We have prepared such films by epitaxial sputtering, and characterisedthem using x-ray diffraction and VSM measurements. The X-ray results show thatchemical order parameters of up to 0.8 can be achieved by this method. These filmsexhibit an antiferromagnetic to ferromagnetic transition consistent with those seenin literature.References:

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1. G. Shirane et al, Phys. Rev. 134, 1964.2. F. de Bergevin and L. Muldawer, J. Chem Phys. 35, 1961.3. M. A de Vries et al, New J. Phys. 15 013008, 20134. D. Kande et al, IEEE Transactions on Magnetics, 2011.

Why do Lipid Domains Register? 6

James Goodchild

Molecular and Nanoscale Physics

Since the proposal of the lipid raft theory in 1997, the understanding of laterallipid organisation within phospholipid bilayers has improved dramatically. Modelsystems such as supported lipid bilayers have been instrumental in understandingthe fundamentals of how lipids organise themselves. Phase separated micro-domainstypically form symmetrically, aligning precisely across the leaflets. This is known asdomain registration. However, there is a poor understanding of inter-leaflet couplingmechanisms, with little direct experimental data. Recent simulations have shownthat increasing hydrophobic mismatch should increase the tendency of lipid domainsto from the asymmetric anti-registered state, in order to minimise the increasing linetension.Our aim is to drive the system to spontaneously form in an anti-registered state,and therefore understand the magnitude of the forces driving registration. We in-crease line tension by systematically increasing the chain length of the saturatedlipid in a ternary lipid mixture. AFM was used to image supported lipid bilay-ers, distinguishing different lipid domains by their height and mechanical response.This approach has proven successful, and we present images of anti-registered sup-ported lipid bilayers. AFM force spectroscopy is used to distinguish between thetwo leaflets of a bilayer, through which the orientation of the anti-registered regioncan be determined.

Radio Properties of the CORNISH Planetary Nebulae 7

Tonye Irabor

Astrophysics

Planetary nebulae (PNe) are ionized envelopes of intermediate mass stars. Under-standing these objects and how they evolve will provide constraint on their evolu-tionary models and sequence. The discrepancy in observed and predicted numberof Galactic PNe is likely due to these objects being hidden behind large amounts ofdust, especially at lower latitudes in the Galactic plane, in optical surveys. This canbe overcome by searching at radio wavelengths. The Co-ordinated radio ’N’ Infraredsurvey for high-mass star formation (CORNISH) survey, is a radio continuum surveyof the inner Galactic plane, covering Galactic longitude 10 deg < l < 65 deg andlatitude |b| < 1 deg with a resolution of 1.5 arcseconds. With the resolution and sen-sitivity of the CORNISH survey there is a uniform detection of relatively compact,

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flux limited PNe within the |b| < 1 deg region, where extinction is high. CandidatePNe from this survey were visually selected by the CORNISH team, using availablehigh resolution, high sensitivity multi-wavelength image data. This radio selectedsample is relatively complete compared to previous surveys within this region. Re-sults from their radio properties show a relatively young and compact PNe samplewith which to compare to model predictions.

Microfluidic device fabrication for the imaging ofCaenorhabditis elegans in a dorsoventral aspect for the

study of its sensory neurons7

Jinyang Chung

Molecular and Nanoscale Physics Physics

C. elegans is a model animal which has highly developed sensory system. 11 pairs ofsensory neurons are located left and right side in the head symmetrically. However,it was hard to investigate both neurons at once because the worm crawls laying oneither side. Here, we fabricated a microfluidic device to trap the worm, treat thestimulus to it and image it from the side-view (dorso-ventral view). So, it enabledto observe a pair of the neurons in the same focal plane. Then, a worm geneticallymodified to express calcium indicator protein (GCaMP) in its ASH neurons wasimmobilized in the device and stimuli (NaCl) was treated to the amphid of theworm. As a result, the intensity of fluorescence in the neurons, indicating Ca ionintake and the depolarization of the neuron, increased when the amphid touched thesalt flow. The side-view device is expected to be used for investigating other pairsof sensory neurons.

Simple fabrication of scalable Liquid Crystal Elastomerswith low glass transition temperatures8

Devesh Mistry

Soft Matter Physics

Liquid crystal elastomers (LCEs) are a class of elastomeric systems functionalisedwith liquid crystalline moieties. Proposed applications include novel actuators, sen-sors and substrates for flexible electronics. The anisotropy of the liquid crystallinemoieties is transferred to the polymer backbone of the elastomer and leads to at-tractive properties such as: >300% shape changes when stimulated, for exampleby heat, light or humidity, Anisotropic elasticity with the emergence of so calledsoft-elasticity, Exceptionally large birefringences induced by modest stresses. Thefirst LCEs were produced using siloxane based systems but were complicated toproduce and had limited possible geometries. More recently, simpler acrylate andthiol systems have allowed complex geometries which allow full exploitation of theliquid crystallinity of the elastomers. However, current acrylate and thiol systems

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suffer from high glass transition temperatures preventing room temperature appli-cations and/or require commercially unavailable monomers. Both these problemsare a roadblock to the rapid development of novel LCE devices by the community.In this work we have produced an acrylate LCE with a low glass transition tem-perature and with entirely commercially available materials. Thermal, optical andmechanical tests confirm the LCE nature of the material and we demonstrate theease of synthesis requiring little specialist equipment.

Central Broadcast Quantum Cryptography 9

Beth Newton

Theoretical Physics

Quantum cryptography allows two parties, Alice and Bob, to share a secret key.This key can then be used to encrypt messages between them, allowing uncondi-tionally secure communication. Most quantum cryptographoc systems require adirect quantum communications channel between Alice and Bob. In implimentablesystems, this communications channel almost always takes the form of a fibre opticcable, limiting the range of applications for which it can be used. We are looking atways of using quantum techniques to share secret information between two partiesover a central broadcast system (for example a satellite broadcast or wifi router).The use of microwaves rather than the usual visible or near IR wavelengths enableskey exchange over free space as well as greater distances than the current quantumsystems. In addition, due to the lack of cabling, this system has the potential toprovide seperate secure keys for a number of different end users (i.e. multiple Bobs).The eventual aim is to produce a system as close as possible to current classical sys-tems to enable a near seamless uptake of the technology, increasing the security withminimal impact to the product design.

Spin ordering at the interface between diamagneticCu/amorphous Carbon 10

Shoug Alghamdi

Condensed Matter Physics

Spintronics falls under the most active areas of research and fast rising disciplineswithin science and technology. Organic semiconductors (OSCs) is a fascinatingtopic both for essential scientific research and for future applications. In addition toconsiderations of recyclability, cost, and/or mechanical flexibility, organic moleculesusually have a feeble spinorbit interaction leading to a long spin diffusion length.In the case of nanocarbon materials without hydrogen bonds, spin polarization canbe maintained for even longer distances and times thanks also to weak hyperfineinteraction. RF sputtered amorphous carbon (a-C) thin films display outstandingmechanical, chemical, optical and thermal features, which are accredited to theflexibility of the sp1, sp2 and sp3 concentration hybridization sites. The interfaces

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between Cu and amorphous carbon lead to transfer charges from copper to theorganic molecules. The resulting modifications to the density of states of the metaland carbon allotrope, coupled with changes in the exchange interaction can makethese interfaces ferromagnetic at room temperature, similar to the effect observedin C60/nonmagnetic systems, but with the advantage of using a cheaper sourcematerial and more compatible method of deposition [1]. Initial results show magneticordering at room temperature that depends on the Cu thickness: samples withthe structure a-C (5 nm)/ Cu (3 nm)/ a-C (5nm) show a magnetization of upto 95 emu/cc. This study is consistence with C60/ Cu study [2] which showedhybridization effect between the 3d metal bands and molecular pz orbital leading toa large charge transfer and emerging magnetization.

Developing the use of microuidics for the detection of singlemolecules of biomarker and single cell analysis11

Liam Hunter

Molecular and Nanoscale Physics Physics

Cancer biomarker detection is an important step in diagnosis of disease. Early de-tection of low concentrations of biomarkers leads to quicker treatment and improvedprognosis. We are using optical fluorescence techniques combined with microfluidicsto determine biomarker concentration in femtolitre water droplets. We have suc-cessfully used this method to detect single enzyme molecules. This system will beemployed to detect low concentrations of Prostate Specific Antigen (PSA) and otherbiomarkers. This project aims to use this method with human patient samples forPSA detection.We are also developing a multi layered poly-dimethylsiloxane device for selectivetrapping of single cells. Once trapped, these cells can be exposed to various envi-ronmental factors and observed. This device will allow the selective release of singlecells for further analysis and phenotyping.

Interaction of astrophysical flows with clouds and filaments12

Kathryn Goldsmith

Astrophysics

The flow of hot, high velocity gas through the interstellar medium (ISM) is knownto play an important role in both star formation and (on much larger scales) theformation and evolution of galaxies. High velocity shocks and winds are ubiquitouswithin the ISM, particularly in regions of star formation. In addition, dense cloudsand filaments are similarly prevalent. A study of the interaction of shocks and windswith both clouds and filaments is, therefore, important for a complete understandingof the gas dynamics of the ISM. We perform numerical simulations of the interactionof winds and shocks with clouds and filaments. We investigate the effect of varioushydrodynamical and magnetohydrodynamical processes on the evolution of the cloud

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by varying the Mach number of the flow, cloud density contrast, magnetic fieldstrength and orientation, and cloud aspect ratio and angle to the flow, and comparethe cloud morphology and lifetime between simulations. We determine how theevolution of filaments compares to spherical clouds of the same density contrast,and investigate the difference between wind-driven and shock-driven interactions.Future work will build on these investigations.

Voltage control of molecular spin ordering as probed by lowenergy muon spin rotation. 13

Matthew Rogers

Condensed Matter Physics

C60 is a unique molecule, its molecular levels exhibit a high degree of degeneracywith weak intermolecular bonding. Hence, it can be readily sublimated as a semicon-ducting, thin film for spintronic applications. One interesting facet of the moleculeis the spin polarized charge transfer it supports at the interface. It has even beenshown to induce magnetism in non-magnetic materials thanks to charge transferand the resulting change to the density of states of the metal. In this project we ex-plore the potential for magneto-electrical and magneto-optical coupling phenomenain hybrid metal/fullerene interfaces. We start by proposing a method of alteringinterfacial electron transfer via electrical gating of fullerene films interfaced withmagnetic and semiconducting substrates. Manipulating the energy barrier height atthese interfaces should lead to changes in the population of spin polarized electronswithin the molecule. Spin dependent charge trapping in fullerene based magnetictunnel junctions have been investigated by use of X-ray absorption and X-ray mag-netic circular dichroism, where large changes in the molecular band structure isseen. Wide area molecular junctions and electronically gated films have been usedto further study electrical effects on spin states in the molecule by low energy muonspin rotation.

Investigating Cold Shock Protein Interactions with singlestranded DNA using Single Molecule Force Spectroscopy 14

Ellen Kendrick

Molecular and Nanoscale Physics Physics

Single-molecule force spectroscopy (SMFS) provides a direct mechanical measure-ment of molecular forces caused by a single protein unfolding or a complex unbind-ing. The aim of this project is to apply SMFS techniques to the investigation ofprotein-DNA interactions. Combining SMFS with bulk binding studies will helpus to understand the impact of DNA binding on stability and dynamics of eachmacromolecule. The cold shock protein (CSP) from the bacterium Bacillus subtil-lis, BsCSP was chosen as a good candidate to investigate ssDNA-protein interactions

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as previous studies in our group have demonstrated that BsCSP has a clear mechan-ical fingerprint in SMFS experiments. BsCSP regulates biological functions and iskey for adapting systems to cold shock. The function of CSPs is therefore highlytemperature specific and involves the binding of nucleic acids over a temperaturerange that depends on the natural environment of the organism. When looking atusing proteins as the building blocks for biomaterials, an understanding of whatcauses the mechanical characteristics and how they are affected by binding is anessential step. Utilising the effect of binding in the design could lead to materialswith mechanical properties that are responsive to biologically relevant signals.

Tracking of Particles at Defects in Nematic Liquid Crystals15

Anne Helen Macaskill

Soft Matter Physics

Understanding the interaction between colloidal particles and defects in liquid crys-tals is a step towards the construction of novel photonic structures and liquid crystaldisplays. While there are a number of theoretical studies on the influence of defectson particles, the interactions have not yet been thoroughly quantified by experi-ment. In this project, optical tracking software was used to record the trajectory ofparticles near to and away from defects. The mean square displacements of particlepositions were used to quantify the confinement associated with defects.

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