New results in an old metal: slow dynamics using X-ray speckle Eric D. Isaacs Center for Nanoscale Materials, Argonne National Laboratory The James Franck Institute, The University of Chicago
Dec 19, 2015
New results in an old metal: slow dynamics using X-ray speckle
Eric D. IsaacsCenter for Nanoscale Materials, Argonne National
LaboratoryThe James Franck Institute, The University of Chicago
Advanced Photon Source
Center for Nanoscale Materials
Outline
Texture and multiphase coexistenceFluctuations of domain wallsWider implications
– ‘quantum’ soft matter– domain wall resistivity
Sandpiles (10-3-10 m)
Avalanches(10-103 m)
tectonic plates (102-106 m)
Abrikosov vortexlattice (10-7 m)
100km
1 km
1 m
1 mm
1 m
1 nm
1Å
Liquid dropletspinned on roughsubstrates(10-4 – 10-2 m)
Magnetic domains(10-8-10-4 m)
Charge-, Spin-density waves(10-10-10-7 m)
Collective dynamics in the presence of quenched disorder
Jamming, shear flow in granular materials, colloids (10-9–10-2 m)
S. Mori et al., Nature 392, 473 (1998)M. Uehara et al., Nature 399, 560 (1999)
CMR manganites
Mesoscale Structure in Strongly Interacting Fermi Systems
M. Bode, et al., Nature (2006)
AF iron
engineering antiferromagnets
No need to look at complicated material to find complexity
Chromium and its common alloys are ‘simple’ bcc metals, exhibiting complex behaviors including:
• Only elemental material w/SDW.
• Spin-density wave ground state at 311 K due to Fermi-surface nesting.
•Spin-flip transition at 123 K.
• Quantum critical behavior: drive TN to zero by doping with V or by applying pressure.
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Feng, et al.
magnetic and charge x-ray contrast in chromium
Spin Density Wave satellites
Charge Density Wave satellites
Real Space:
Reciprocal Space:
Bragg peak
Spin Density
Chargedensity
Texture and multiphase coexistence
For science & engineering, need to image individual domains & walls between them - but visible light does not couple & neutrons average over a large sample
Atomic-scale light - X-rays
outermost zone
1992: 0.5 m
2007: 30 nm
Force Radiation
-eE electric dipole“Thomsonscattering”
-eEmagnetic quadrupole
After F. de Bergevin and M. Brunel, Acta Cryst. A 37 314 (1981).
EE
EH
e-
-e
Magnetic X-ray Scattering (Classical Picture)
electric dipole)( H⋅∇ H E
e-
.
.
.
€
I ∝ hωmc 2( )
2
r02 ≤10−4 r0
2Magnetic scattering is very weak:
e-
€
I ∝ r02
100
Evans et al., Science 295, pp. 1042-1044 (2002)
8.6
8.7
0
5
10
110 120 130 140
2
3
41
H=2 kG
H=0
T (K)
10 m 2
4 3
1
10 m 10 m 10 m
10 m 10 m 10 m 140 K 130 K 125 K 120 K
110 K 119 K 115 K ≤1
≥4
Q || (001) and S⊥Q
Q ⊥ (001) or S||Q
Magnetic domain nucleation
Q-domains
10 m
3-4 nm
REAL SPACE:
RECIPROCAL SPACE:
Domain Dynamics using Coherent X-rays - Simulation
X-ray Coherence
Young’s double slit experiment.Intensity varies as
Advanced Photon Source: • 10 x 40 m2 slits• X-ray flux ~ 3x109 ph/s• Coherence factor: A ~ 15 %
coherence factor
€
I = I0 1+ Acos 2πLsin θ( ) /λ( )[ ]
Speckle Pattern
10 m
Q~10-2 Å-1
Resolution:
€
~ π /ΔQ
~ 50nm
X-ray Photo Correlation Spectroscopy (XPCS)
…
€
g2(r
Q ,t) = 1+ A[S(r
Q ,t)/ S(r
Q )]2 =I(
r Q ,t )I(
r Q ,t +τ )
τ
I(r
Q ,τ )τ
2
t + Δt
…
t
t + 2Δtt + 3Δt
t + 4Δt10 m
autocorrelation function
CDW domains in real space
150K
O. G. Shpyrko et al., Nature (2007)
Autocorrelation function, g2(t)
150K100K
Autocorrelation function, g2(t)
150K100K
70K
Autocorrelation function, g2(t)
150K100K
70K40K
Autocorrelation function, g2(t)
150K100K
70K
40K
30K
Autocorrelation function, g2(t)
30K
17K
Autocorrelation function, g2(t)
30K
17K
4K
Autocorrelation function, g2(t)
Compressed exponentialexp[-(t/s)] with ~1.5
But why?
Bragg speckle
Autocorrelation function, g2(t)
Classical Arrhenius model
1 1( ) expS RB
ET
k T − − ⎛ ⎞
= −⎜ ⎟⎝ ⎠
Quantum Tunneling model:
1 1 1( ) expS QM RB
ET
k T − − − ⎛ ⎞
= + −⎜ ⎟⎝ ⎠
Barrier E~ 250KRelaxation frequency R
-1 ~ 0.1 Hz
1 2
Real Spaceelemental switching block,
w/ volume (/2)3, =3-4 nm
2
1
1
1
22
3
3
Momentum Spacetransfer of intensity from
satellites 1 to 2 due to switch
1 2
Where could this come from?
Wider implications…’Soft’ quantum matter
Jamming (similar to Glass Transitions)
Repulsive Interactions:
J. Liu and S. Nagel, Nature 396, 21 (1998)
U
100 m
Fluid Solid
Slow Dynamics in Soft matter
Final relaxation: “compressed exponential”
exp[-(t/ f)] with ~1.5
Onion gel
L. Ramos and L. Cipelletti, Phys. Rev. Lett. 87, 245503 (2001)
B. Chung et al., “Microscopic Dynamics of Recovery in Sheared Depletion Gels”Phys. Rev. Lett. 96, 228301 (2006)
R. Bandyopadhyay et al., “Evolution of Particle-Scale Dynamics in an Aging Clay Suspension”, Phys. Rev. Lett. 93, 228302 (2004)
Aging in Soft Matter with XPCS (gels and clays):internal stress speeds up relaxation
g2(q,t) exp[-(t/f) 3/2], f q-1
Source of Stress in Hard Matter - Spin/Charge Density Wave Pinning Defects
H. Fukuyama and P. A. Lee, Phys. Rev. B 17, 535 (1978)P. Littlewood and T. M. Rice, Phys. Rev. Lett 48, 44 (1982)
Phase elasticity Pinning potential
summary• X-ray photo correlation spectroscopy (XPCS) allows
measurement of dynamics of antiferromagnets at nanometer length scales (finite-q).
• Dynamics are strongly reminiscent of ‘glassy’ collective behavior in disordered systems seen universally in soft matter near jamming transition, but, …
• … in solid-state system, quantum tunneling provides additional channel for relaxation.
• Antiferromagnetic domain walls give rise to measurable electron scattering: need full calculation of 3D resistivity tensor.
X-ray Revolution (Future is Bright!)
incandescent light sources (incoherent)
lasers (coherent)
Moore’s law for X-ray Sources
18 ordersof magnitudein 5 decades!
12 ordersof magnitudein 6 decades
(Energy Recovery Linacs)
Developments for Nanoscience
1. Nano-scale focusing - CNM’s Hard X-ray Nanoprobe @ the APS
2. Coherence (X-ray “Lasers”)• Lens-less imaging• X-ray photo correlation spectroscopy
Proposed Energy Recovery Linac at Cornell, Argonne
X-ray Free Electron X-ray Free Electron Laser at SLAC Laser at SLAC (opening in 2009)(opening in 2009)
Hard x-ray spot size vs. year
Spo
t si
ze (
nm)
WSi2/Si
Zone plate Multi-layer Laue lens
CNM/
M. A. Pfeifer et al., Nature 442, 63–66 (2006).E.D. Isaacs, News&Views, Nature 442 (2006).
O. Shpyrko, et al Nature 447, 68–71 (2007)
X-ray photo correlation spectroscopy (XPCS) - dynamics with high spatial resolution
Two things we can do with coherent x-rays
Structure of non-periodic structures - we can invert speckle pattern, solving the phase problem for ‘lens-less’ imaging. Long-range order no longer required.
Speckle Pattern and Spatial Resolution
Q~10-2 Å-1
Spatial resolution:
€
~ π /ΔQ ~ 50nm
Resolution is coherent flux-limited:IBragg ~ 1/q2
Current resolution: ~ 50 nm we need factor of 100 in coherent flux to achieve 5 nm.
= smallest object that can contribute to speckle
Can we image disorder directly?
M. A. Pfeifer et al., Nature 442, 63–66 (2006).
Autocorrelation Function and Temporal Resolution
Resolution is coherent flux-limited:g2(t) ~ intensity-intensity correlations
Statistics:5% error bars 1 second resolution
we need factor of 100 in coherent flux to achieve msec resolution. spatial + temporal: need 10,000 x
Can we image single quantum rotor directly?
Coherent (lens-less) X-ray Imaging
Can we invert speckle of embedded, irregular structures to obtain 3D real-space images? (ptychography)
1. Reveal internal CDW phase information (topological defects, phase strain) with ~ 50 nm resolution currently
2. 3D movies of nanoscale fluctuations (FEL, ERL)
3D speckle (momentum space):
conclusions• Complex behavior in simple substance
– Textures– Quantum fluctuations - slow [and fast seen
w/neutrons]– Beginning of AFM domain wall engineering
• Future: collective dynamics using bright coherent sources
10 m
‘Quantum’ Speckle Collaborators
Dr. Oleg Shpyrko, Center for Nanoscale Materials, Argonne National LabJonathan Logan, Clarisse Kim, U. Chicago
Rafael Jaramillo, Dr. Yejun Feng, Prof. Tom Rosenbaum, U. Chicago
Prof. Paul Evans, U. Wisconsin, Madison
Dr. Paul Zschack, Dr. Michael Sprung, Dr. Alec R. Sandy(Advanced Photon Source, Argonne)
Prof. Gabriel Aeppli, Prof. Ian Robinson(University College, London)
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XPCS and other spatio-temporal probes
Scattering Vector Q [Å-1]
Length Scale [Å]
Freq
uen
cy [
Hz] E
nerg
y [e
V]
Raman
Brillouin
XPCSlaserPCS
IXS
Spin-Echo
INS
Advantages• Shorter lengthscales• Non-transparent materials• Charge, Spin, Chemical and atomic structure sensitivity
Disadvantages• Need coherent x-ray sources!
S(q, ) map:
Aging of Soft Matter systems undergoing ‘jamming’ transitions (using laser speckle PCS)
Colloidal particles gel
100 101 102 103 104 1050.00
0.25
0.50
0.75
1.00
q (cm-1)2493384596188331133152820582782375650666745
C:\Backup Penn\Arnie\lucacip\doc\Papers\PRL_GELPoly\Fig2
(sec)
0 2x1011 4x1011-2
-1
0
(q)3/2 (cm-1sec)3/2100 101 102 103 104 105 1060.0
0.2
0.4
0.6
0.8
C:\lucacip\Origin\DLS CCD\000709_F108_000329B
21 deg 45 deg 80 deg g2OKbaselin
g2OKbaselin g2OKbaselin StretchedExp simulation
t (sec)t
f(q,
t)Micellar polycrystal Conc. Emulsion
f(q,) exp[-(t/f) 3/2], f q-1
review: Cipelletti et al., Faraday Discuss. 123 (2003)
What is the relationship between bulk properties (eg, transport) and mesoscale structure?
Michel et al., PRB 44, 7413 (1991)
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Time (sec)
B. Raquet et al., Phys. Rev. Lett. 84, 4485 (2000).
La1-xCaxMnO3 films
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D. van Harlingen, et al., 2006
underdoped YBCO nanowires
chromium films
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