Oleg Shpyrko- XPCS Studies of Antiferromagnetic Domain Wall Dynamics in Elemental Chromium

8/3/2019 Oleg Shpyrko- XPCS Studies of Antiferromagnetic Domain Wall Dynamics in Elemental Chromium

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XPCS Studies of Antiferroma netic Domain

Wall Dynamics in Elemental Chromium

Oleg ShpyrkoDepartment of Physics,University of California San Diego


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Crunchy & Squishy Physics

Hard Condensed Matter

Soft Condensed Matter

Gels, Colloids Metals, Alloys

Polymers, Fluids

Liquid Crystals

Oxides (Insulators)

Semiconductors

Bio-materials Magnets


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XPCS and other spatio-temporal probes

Length Scale [] XPCS is the extension

S(q, ) map:

z]

INS

scattering probe(laser PCS)

ue

ncy[ ne

rg

y[

aman

Brillouin

IXS

S in-Echo

Pros: Smaller lengthscales

Non-transparent

Fre

V]

XPCSlaserPCS

Charge, Spin, Chemicaland atomic structuresensitivity

Cons: Need fully coherentx-ray sources!

Scattering Vector Q [ - ]


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XPCS and other spatio-temporal probes

Length Scale []S(q, ) map:

z]

INS

ue

ncy[ ne

rg

y[

aman

Brillouin

IXS

S in-Echo

Fre

V]

laserPCS ???

Courtesy G. B. Stephenson

New X-ray Sources(NSLS-II, LCLS)

Scattering Vector Q [ - ]


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Mesoscale Texture in Strongly Interacting Fermi Systems

High-Tc cupratesCoexistence of multiple phases:

superconducting and AF domains (stripes orcheckerboards) in underdoped high-Tc cuprates

E. Dagotto, T. M. Rice, Science271, 618 (1996).

AF and FM domains in CMR manganitesAFM domains with orthogonal orientation ofs in- and char e- densit waves in Cr

CMR manganites

. anagur et a ., ature , .

What underlies such mesoscopic texture?

Is the texture (domain structure) frozen?

What are the effects of thermal andquantum fluctuations?

AFM chromium

P. G. Evans et al., Science(2002)

S. Mori et al., Nature392, 473 (1998)

M. Uehara et al., Nature399, 560 (1999)


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Brief Review - X-ray Speckle, the early years:

Speckle of (001) Cu3Au peak Speckle of the Fe3Al (1/2,1/2,1/2)

M. Sutton et al., The Observation of

Speckle by Diffraction with Coherent X-rays Nature352, 608-610 (1991).

super- a ce re ec on s ow ng rozen- n sor er.b) Zoom of the central region in a) where the speckle

structure is obvious.Grubel et al., ESRF News (1995)


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Binary Alloys:

Cu AuSutton et al., Nature 1991, PRL 2005

Fe3Al

Brauer et al., PRL 1995Mocuta et al., Science 2002

, , ,Stadler et al. 2004-7


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Equilibrium: Non-equilibrium:

A. Fluerasu et al., Phys. Rev. Lett. 94, 055501 (2005)M. Sutton et al., Opt. Exp. (2003)

Quenched Cu3Au


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- :CuPd binary alloy:

Ludwig et al., PRB 72, 144201 (2005)


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Charge and Spin-ordered systems:

Nb3Se (classic CDW system)Sutton, Brock, Thorne et al., J. Phys. 2002, PRB 2001

Shpyrko, Isaacs et al., Nature 2007


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Charge and Spin-ordered systems:

Ho ilms helical AFMKoning, Goedkoop, PRL 2007

- -. . Turner, Hill, Kevan et al., arxiv (?) 2008Nelson, Hill, Livet et al., PRB 2002


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Studies of antiferromagnetsare morec a eng ng t an t ose o erromagnetsNet magnetic moment = 0

Complex relationship between mesoscalephases (spin, charge, lattice) andh sical ro erties

Spin domains in CrP. G. Evans, E. D. Isaacs et al.,Science295 1042 (2002)

How can we study mesoscale

Charge/spin density

dynamics in the bulk?X-rays: Scannin X-ra Microsco

10 m

10 m (slow dynamics)

X-ray Photon Correlationo eren x-ray

speckleSpectroscopy or XPCS (faster)


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Spin Density Wave (SDW) in Chromium:

Commensurate SDW (C-SDW)ave o ows per o c ty o

underlying atomic lattice

-Modulation period incommensuratewith lattice periodicity

For chromium incommensurabilit arameter is =0.037 at room T(period is -1~28 times the lattice constant)


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Charge, Spin and Lattice order parameters:Rea Space:

S in

Density

Reciprocal

Space:

density

Charge DensityWave satellites

Spin Density Wave

satellites Bragg peak


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Microscopic Magnetic Domains in Chromium:

Scanning X-ray Microscopy:

[0, 0, 2-2] Charge-density wave satellite

bulk robe micron-sized

10 m

penetration depth) spin, charge, latticeand chemical sensitivity


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Domain Wall Fluctuations inn erromagne s


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Magnetic domain wall fluctuations

21

3

1

22

3

Real Space:

Momentum Space:e emen a sw c ng oc ,

w/ volume (/2)3

, =3-4 nm

trans er o intensity rom

satellites 1 to 2 due to switch


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Random Telegraph Noise in Cr (thin films):

Discrete steps inelectrical resistivity

Slow (1 s -100 s)

-

Is t is omainswitching?

R. Michel, M. Weissman, Phys. Rev. B44, 7413 (1991).


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Random Telegraph Noise in other materials:

angan es a1-x ax n 3 :2 4

F. Kidwingira, D. J. Van Harlingen et al.,Science314, 1267 (2006)

B. Raquet et al., Phys. Rev. Lett. 84, 4485 (2000)

Chromium:

R. D. Merithew et al., Phys. Rev. Lett. 84, 3442 (2000)

R. Michel, Phys. Rev. B44, 7413 (1991)


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Random Telegraph Noise measurements:

~100 nm

focused x-ray beam

~100 nm (0.5 m)


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X-ray Photon Correlation Spectroscopy (XPCS):

t + 4t10 m

t + 2t

t +tt

speckle pattern

t + tt t + 2t t + 3t t + 4t

O. G. Shpyrko et al., Nature447, 68 (2007)


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CCD camera

2(0,0,2 )Q

=

r

r

'k

k


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Control experiment: Bragg Speckle

Quasi-static Brag speckle(line scans from 2D image): X-ray Bragg speckle

6-hr avera e



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Bragg, 300K: (total 6 hrs) linescans

x 1 06 D : \ b ra g g _ R T _ 1 5 x 4 0 _ 6 h rs \ b ra g g _ R T _ 1 5 x 4 0 _ 6 h rs _ 0 0 0 0 1 -0 7 0 1 0 .i m m

L in e = 7 5 , F ra m e : 1 -1 4 0 1F r a m e : 1 4 0 2 -2 8 0 1

5

6F r a m e : 2 8 0 2 -4 2 0 1F r a m e : 4 2 0 2 -5 6 0 1F r a m e : 5 6 0 2 -7 0 0 1

CDW, 4K:6 hrs3

4

3

x 106 D:\cdw_4K_15x40_2\cdw_4K_15x40_2_00001-05010.imm

Line=70, Frame:1-1001

Frame:1002-2001

Frame:2002-3001

Frame:3002-4001Frame:4002-5001

1

2

2

.

2 0 3 0 4 0 5 0 6 0 7 0 8 0

0

1

1.5

20 25 30 35 40 45 50 55 60 65 70

0.5


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Autocorrelation function g2(t):Multiple relaxation timescales

1

17K,

fit =3000sfit 1=3300s 2=40s

0.8

0.6

2(q,t

)/S2(q,0

)

40 s2(

t)-1]/

0.4

S

[

2

22

),(),()](/),([1),(

tQItQIQStQSAtQg

r

rr

rrr+

=+=

0.2

),( QI

101

102

103

104

0

time [s]

, s

time [s]10 100 1,000 10,000


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Autocorrelation data:

Bra s eckle



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Classical Arrhenius model

1 1 E =

Quantum Tunneling model:

Bk T

1 1 1( ) expS QM RB

Tk T

= +



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Slow Dynamics in Soft Matter

1 .0Onion gel

0 .6

0 .8

(t,q) -relaxation

(cage)

0 .2

0 .4 -relaxation(collective)

compressed

1 0-7

1 0-5

1 0-3

1 0-1

1 01

1 03

1 05

0 .0

Final relaxation: compressed exponentialf t =ex - t/ with ~1.5 and -1

L. Ramos and L. Cipelletti, Phys. Rev. Lett. 87, 245503 (2001)


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Aging of Soft Matter under jamming transition(using Laser speckle PCS)

reviewed in L. Cipelletti et al., Faraday Discuss. 123 (2003)

Colloidal gels

1.00

0.8

Micellar polycrystal ConcentratedEmulsions

0.50

0.75q (cm-1)

24933845961883311331528

(q,

)0.4

0.6

g2

(t)-1

21 deg45 deg80 deg

q,

t) 0.5

.

f(q,

t)

100 101 102 103 104 1050.00

0.25

2058

2782375650666745

100 101 102 103 104 105 1060.0

0.2

C:\lucacip\Origin\DLS CCD\000709_F108_000329Bt (sec)t

f(

101 102 103 1040.0

sec

f(q,) exp[-(t/f)1.5

], f q-1


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What does next generation ofsources - r ng us

Brightness=Coherent Fluxbrightness=1021 Photons/sec/mm2/mrad2/0.1%BW or=Flux/emittance/0.1% BW

Ratio of source emittance to diffraction limited emittance 2/4 iscoherent fraction

. n ance spat a reso ut on or t e same temporascale) scales as rmin~1/I

2. Enhanced temporal resolution scales as min

~1/I2


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Intensity

~2-3 x 10-3

-1

~10-2 -1

QBra

i


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Intensity

~2-3 x 10-3

-1

I ~ (Q)-2

increase incoherent flux

(brightness)

~10-2 -1

~5x10-2 -1~5 fold increase

QBra

Instead of /10-2

-1

~30 nm, resolution becomes ~6 nm


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Enhanced time resolution:For CDW in Cr we could getreasonable statistics at


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-

For Cr SDW satellite at APS ~ 1 ct/sec (coherent flux)Factor of 30 helps, but realistically need a factor of ~103+ (!)

Orbital Order:Second Order

Order

Nelson, Hill et al., PRB 66, 134412 (2002) T emperaturePressure, Magnetic field


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Chromium Work -

Oleg Shpyrko and Prof. Eric Isaacs (Center for NanoscaleMaterials, Argonne and Physics Dpt., University of Chicago)

Yejun Feng, Rafael Jaramillo, Jonathan Logan and Clarisse Kim.

Paul Zschack, 33-ID

Michael S run 8-IDSuresh Narayanan, 8-IDAlec R. Sandy, 8-IDAdvanced Photon Source Ar onne

Gabriel Aeppli(U. College London)

Oleg Shpyrko- XPCS Studies of Antiferromagnetic Domain Wall Dynamics in Elemental Chromium

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