Dynamical control in quantum materials

Andrea Cavalleri

Max Planck Institute for the Structure and Dynamics of Matter Hamburg

Department of Physics

University of Oxford

Complex Materials

Strong correlations produce collective giant responses to small external perturbations.

Such responses are often functionally relevant.

One important goal is to CONTROL complex materials, induce these phenomena at higher

temperatures or amplify their responses

PresenterPresentation NotesMaterials with strong correlations often posses a wide variety of competing phases with different and unconventional properties. This results in very intricate phase diagrams, like the collection shown here for some representative complex oxides taken from this review paper by Dagotto. Im not going to describe these systems in any detail but instead want to highlight a number of important examples, such as metal-insulator transitions, colossal magnetoresistance and the famous example of high-temperature superconductivity.

What these materials have in common is that strong correlations mean they exhibit collective giant response to small external perturbations, be that pressure, temperature, electric or magnetic fields.

These responses are often of functional relevance to technological applications, superconductivity being an obvious case.My major research question is whether we can force materials to exhibit these responses at higher temperatures, ideally room temperature?

Chemical substitution

Chemical doping

Pressure and magnetic fields

Control and Optimization: Established Routes

Alloying

Driven systems

Driven solids are different

Dynamical modulation can create effective energy landscapes and new functionalities in quantum solids

PresenterPresentation NotesMaterials with strong correlations often posses a wide variety of competing phases with different and unconventional properties. This results in very intricate phase diagrams, like the collection shown here for some representative complex oxides taken from this review paper by Dagotto. Im not going to describe these systems in any detail but instead want to highlight a number of important examples, such as metal-insulator transitions, colossal magnetoresistance and the famous example of high-temperature superconductivity.

What these materials have in common is that strong correlations mean they exhibit collective giant response to small external perturbations, be that pressure, temperature, electric or magnetic fields.

These responses are often of functional relevance to technological applications, superconductivity being an obvious case.My major research question is whether we can force materials to exhibit these responses at higher temperatures, ideally room temperature?

Take a pendulum and vibrate its pivot point:

P.L. Kapitza, Dynamic stability of a pendulum with an oscillating point of suspension, Zh. Eksp. Teor. Fiz. 21, 588 (1951)

L.D. Landau and E.M. Lifschitz Mechanics (Pergamon, Oxford 1976)

Driven systems: new energy landscapes

Kapitza Pendulum Normal Pendulum

PresenterPresentation NotesA key approach to this aim comes from our understanding of driven systems. In particular more than 100 years of study has established that driven systems can often exhibit new regions of stability not seen in equilibrium. A famous example is the so-called Kapitza pendulum, which is just a normal pendulum with a pivot point that undergoes rapid vertical oscillation. In this movie I show a Kapitza pendulum and a normal pendulum, both have gravity pointing downwards as usual and are subject to friction. The striking behaviour we see here is that by driving the pivot point we can make the inverted position of the pendulum a stable point, and the usual downwards equilibrium point unstable. Importantly there is no feedback control here or precise tuning, so long as you driving the base much faster than the natural frequency with small amplitude then this physics is robust.

The big question does such an effect occur in strongly-correlated systems like I described earlier if they are driven by vibrations in the right way?

Dynamical Stabilization

Take a saddle and spin it:

Dynamical Stabilization: the Paul trap

W. Paul, Nobel Lecture in Rev. Mod. Phys. 62, 531 (1990).

Take a saddle and spin it:

Frequency scales

Driving frequency

We want to excite collective modes of quantum materials beyond their linear response

PresenterPresentation NotesMaterials with strong correlations often posses a wide variety of competing phases with different and unconventional properties. This results in very intricate phase diagrams, like the collection shown here for some representative complex oxides taken from this review paper by Dagotto. Im not going to describe these systems in any detail but instead want to highlight a number of important examples, such as metal-insulator transitions, colossal magnetoresistance and the famous example of high-temperature superconductivity.

What these materials have in common is that strong correlations mean they exhibit collective giant response to small external perturbations, be that pressure, temperature, electric or magnetic fields.

These responses are often of functional relevance to technological applications, superconductivity being an obvious case.My major research question is whether we can force materials to exhibit these responses at higher temperatures, ideally room temperature?

Nonlinear Lattice Control

Mode selective lattice excitation

Dynamically drive one or few normal mode

coordinates at ~ 1-10 % displacements

PresenterPresentation NotesMaterials with strong correlations often posses a wide variety of competing phases with different and unconventional properties. This results in very intricate phase diagrams, like the collection shown here for some representative complex oxides taken from this review paper by Dagotto. Im not going to describe these systems in any detail but instead want to highlight a number of important examples, such as metal-insulator transitions, colossal magnetoresistance and the famous example of high-temperature superconductivity.

What these materials have in common is that strong correlations mean they exhibit collective giant response to small external perturbations, be that pressure, temperature, electric or magnetic fields.

These responses are often of functional relevance to technological applications, superconductivity being an obvious case.My major research question is whether we can force materials to exhibit these responses at higher temperatures, ideally room temperature?

Theme 1: Control bond angles and distances

Metal Insulator

Displacing bonds at will: is it possible ?

mid-infra-red light pulse

Insulating

Metallic

Linear response: no displacement

You need anharmonicities

With Roberto Merlin Univ. of Michigan

QIR Q2 term: Oscillations in QIR displace Q2

QIR Q2

Tem

pera

ture

x

FI

AFI

CO/OO

M. Rini et al., Nature 449, 72 (2007)

Pr0.7Ca0.3MnO3: Bending regulates conductivity

In cubic perovskites: stretching -> bending

M. Rini et al. Nature 449, 72 (2007)

M. Foerst et al., Nature Physics 7, 854 (2011)

Theory: electronic structure after rotation

A. Subedi, A. Cavalleri, A. Georges Phys Rev B (2014) $$$ ERC Synergy Grant (2014-2019)

Frozen Phonon

Electronic Structure in the distorted state -> metallic

Theme 2: Controlling superconductivity

Lattice distortions may quench SC Lattice distortions may promote SC

Fradkin and Kivelson, Nature Physcs (2012)

Cuprate superconductors: competing orders

Cooling: La1.84Sr0.16CuO4

Frustrated Superconducting Coupling

Cooling: La1.675Eu0.2Sr0.125CuO4

40 60 800.5

0.6

0.7

0.8

0.9

1.0

Ref

lect

ance

Frequency(cm-1)

LESCO (10K) FitR

efle

ctan

ce

Ref

lect

ance

With Hide Takagi MPI Stuttgart & University of Tokyo

Excite the in plane Cu-O stretch: melt stripes

M. Foerst et al., Physical Review Letters 112, 157002 (2014)

40 50 60 70 80

0.0040

0.0045

0.0050

r/r(

%)

Frequency (cm-1)

Reflectance Model

Cooling: La1.84Sr0.16CuO4 Light: La1.675Eu0.2Sr0.125CuO4

T > Tc

Light Induced Josephson Coupling

D. Fausti et al., Science 331, 6014 (2011)

With B. Keimer MPI Stuttgart

Other cases with charge order: YBa2Cu3O6.6

YBa2Cu3O6.6: Light induced Coupling at 2 X Tc

T = 100 K

W. Hu et al. Nature Materials 13, 705 (2014) S. Kaiser, et al., Phys. Rev. B 89, 184516 (2014)

Induced by light

Induced by cooling T = 10 K

With Bernhard Keimer MPI Stuttgart

TC = 52 K Up to TCO = 150 K

YBa2Cu3O6.5 and YBa2Cu3O6.5: far above TCO

W. Hu et al. Nature Materials 13, 705 (2014)

S. Kaiser, et al., Phys. Rev. B 89, 184516 (2014)

Melting charge order: is that the whole story ?

?

What is the average crystal structure ?

Femtosecond Crystallography at X-ray FELs

(-1,1,1) (0,-1,4)

(-1,0,4) (1,-1,1)

Large displacements of the apical oxygen

R. Mankowski et al. Nature 516, 71 (2014)

d ~ 3 %

Pressure does the same: only less

J. Jorgensen et al. Physica C 171, 93 (1990)

J. G. Huber et al. Phys. Rev. B 41, 8757 (1990) L. E. Schirber et al. Phys. Rev. B 35, 8709 (1987) B. Bucher et al. Journal of Less-Common Metals 164, 165, 20 (1990)

Pressure d ~ 0.5 %

Tc ~ 5 - 15 K

Phononics d ~ 3 %

R. Mankowski et al. Nature 516, 71 (2014)

We would like a crystal with apical oxygen displaced by 3%

Dynamical materials discovery

Theme 2B: Dynamical control of SC pairing

Lattice mediated superconductivity TC (20 K)

The K3C60 superconductor

PresenterPresentation NotesDescribe the bullet points,Describe the structure.Introduce the fact that JT molecular modes are important

(a) (b) (c)

25 K 10 K

Clear superconducting transition: cooling

t1u

Courtesy of A. Subedi

Narrow bandwidth

0.5 eV

Pairing aided by a molecular Jahn-Teller distortion

MIR pump 170 meV

THz probe (2-10 meV)

Optical excitation of molecular vibrations

Light induced phase at 1.2 Tc

M. Mitrano et al. Nature 530, 461 (2016)

M. Mitrano et al. Nature 530, 461 (2016)

Light induced phase at 5 X Tc

light

cooling

A light-induced superconducting like phase

M. Mitrano et al. Nature 530, 461 (2016)

Up to > 100 K

Dynamical enhancement of pairing ?

Nonlinear phononics: many many possibilities

In analogy with nonlinear optics

QIR2 Q2 (lattice control) QIR2 Q22 (phonon squeezing) QIR4 (parametric phonon amplification) QIR1 QIR2ei s (controlling time reversal invariance) QIR2 U (controlling correlations)

PresenterPresentation NotesMaterials with strong correlations often posses a wide variety of competing phases with different and unconventional properties. This results in very intricate phase diagrams, like the collection shown here for some representative complex oxides taken from this review paper by Dagotto. Im not going to describe these systems in any detail but instead want to highlight a number of important examples, such as metal-insulator transitions, colossal magnetoresistance and the famous example of high-temperature superconductivity.

What these materials have in common is that strong correlations mean they exhibit collective giant response to small external perturbations, be that pressure, temperature, electric or magnetic fields.

These responses are often of functional relevance to technological applications, superconductivity being an obvious case.My major research question is whether we can force materials to exhibit these responses at higher temperatures, ideally room temperature?

Andrea Cavalleri

Andrea Cavalleri, M. Foerst, D. Nicoletti, W. Hu, M. Buzzi, J. McIver, S. Rajasekaran, E. Pomarico, F.U. Stein, M. Budden, A. Cantaluppi, A. Cartella, E. Casandruc. B. Liu, R. Mankowski, T. Nova. A. von Hoegen, Th. Gebert, H. Bromberger

Thanks !

Summary

Coherent modulation can lead to the discovery of new non-equilibrium phases of matter not found near equilibrium Understand the non-equilibrium emergent phenomena Explore new paradigms for device applications

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