Synchrotron Beam Slicing - Layout
Femtosecond X-ray studies of strongly Femtosecond X-ray studies of strongly
correlated electron systemscorrelated electron systems
Matteo RiniMatteo RiniMaterials Sciences Division, Lawrence Berkeley National Laboratory
Synchrotron Beam Slicing - LayoutOutlineOutline
Ultrafast X-Ray experiments (BL 5.3.1)
Time-resolved NEXAFS studies of the insulator-to-metal
phase transition in VO2
Time-resolved X-ray diffraction studies of polariton
dynamics in ferroelectrics
Time-resolved X-ray absorption spectroscopy of a
photoinduced spin crossover reaction in solution
Planned X-Ray experiments (BL 6.0)
Structural dynamics and photoinduced phase transitions in
Manganites
Synchrotron Beam Slicing - Layout
fundamental time scale for atomic motionvibrational period: Tvib ~ 100 fs
Atomic Structural Dynamics
• ultrafast chemical reactions
• ultrafast phase transitions
• surface dynamics
• ultrafast biological processes
Ultrafast X-ray ScienceRapidly emerging field of research - Physics, Chemistry and Biology
N
N
FeO
Fundamental Time Scales in Condensed Matter
fundamental time scales for electron dynamicselectron-phonon interaction times ~ 1 ps
e-e scattering times ~10 fscorrelation time ~100 attoseconds (a/VFermi)
Electronic Structural Dynamics
• charge transfer
• correlated electron systems charge/orbital ordering CMR high Tc superconductivity
Understanding the interplay between atomic and electronic structure - beyond single-electron band structure model – correlated systems (charge, spin, orbit, lattice) - beyond simple adiabatic potential energy surfaces
• electronic phase transitions
Fundamental Scientific Challenge in Condensed Matter:Fundamental Scientific Challenge in Condensed Matter:
Synchrotron Beam Slicing - Layout
diffraction angle
time delay
time delay
x-ray probe
visible pumpatomic structure in systems with long-range order/periodicityphase transitions, coherent phonons
detector
time-resolved x-ray diffraction
delay
x-ray probe
visible pumpr
energytim
e
Kedge
abso
rptio
n
Femtosecond X-ray ScienceFemtosecond X-ray Science
ħω
element specificmolecular systems and reactionscomplex/disordered materials
EXAFS – local atomic structure and coordination
NEXAFS – local electronic structure, bonding geometry, magnetization/dichroism
(near-edge x-ray absorption fine structure)
time-resolved x-ray spectroscopy
(extended x-ray absorption fine structure)
surface EXAFS, µEXAFS ….( )( )
2
2sin~)(kr
kkrrf φ+
Synchrotron Beam Slicing - LayoutStrongly Correlated Materials Strongly Correlated Materials
Electrons are strongly interactingElectrons are strongly interacting
2) Interesting phenomena and phase 2) Interesting phenomena and phase transitions at transitions at high temperatureshigh temperatures
1) Unconventional Phenomena (e.g. 1) Unconventional Phenomena (e.g. Mott Mott Insulator, High-TInsulator, High-Tcc superconductivity, superconductivity, Colossal Magnetoresistance, Metal-Insulator Colossal Magnetoresistance, Metal-Insulator transitions,transitions,…….)…….)
~ eV~ eV
Oxides of Transition MetalsOxides of Transition Metals
(e.g. Cu, Mn, Ni, V…)(e.g. Cu, Mn, Ni, V…)
Synchrotron Beam Slicing - LayoutExotic Ground States in Complex Solids Exotic Ground States in Complex Solids
x
y
x
y
(a)
Jahn-Teller InstabilityOrbital order
Charge order
StripesNickelates
Cuprates
Understand interactions between
Atomic arrangements
Carrier doping/ordering
Magnetic ordering
Manganites
a
b
Mn4+
Mn3+
a
b
Mn4+
Mn3+x y
z
x y
z
x y
z
(b)
Spin order
Synchrotron Beam Slicing - LayoutMulti-stability and Phase Competition Multi-stability and Phase Competition
e.g. Manganese OxidesF ( T, H, x, hν, P, E…)
Many competing ground states
Phase Control :
Magnetic Field
Electric Field
Pressure
Photo-excitation
………..
Doping (x)T
emp
erat
ure
Synchrotron Beam Slicing - Layout
Phase of a solidPhase of a solid
Empty band
The “stiffness” of a phase is strongly affected by charge arrangements
Charge ordered band
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to
Hole photo-doping
Electron-photo-doping
The phase of a solid can be controlled by chemical doping or by photo-excitation
Impulsive Photo-doping Impulsive Photo-doping
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Photo-excitation Photo-excitation
Exotic transient phases can be created and controlled
Fundamental correlation mechanisms can be revealed
Giant, ultrafast manipulation of the system’s parameters
to
Product phase
100 fs - 10 meV
1 fs - 1 eV
Synchrotron Beam Slicing - LayoutMonoclinic Rutile
T > 340 K
Insulatorlow T
Metalhigh T
Ultrafast Structural and Electronic Transitions in VOUltrafast Structural and Electronic Transitions in VO22
T < 340 K
3d//
2s2pσ
2pπ
4s
3dπ
3dσ
π bandsdxz,yz
3d//
2s2pσ
2pπ
4s
3dπ
3dσ
R
esis
tivi
ty
Temperature
Eg ≈ 0.7 eV
d// bandsdxy
V0
V4+
O2-
V4+
O2-
VO2
Synchrotron Beam Slicing - LayoutMonoclinic
VO2 RutileT > 340 K
Insulatorlow T
Metalhigh T
T < 340 K
3d//
2s2pσ
2pπ
4s
3dπ
3dσ
π bandsdxz,yz
3d//
2s2pσ
2pπ
4s
3dπ
3dσ
Eg ≈ 0.7 eV
d// bandsdxy
V0
V4+
O2-
V4+
O2-
Mott-Hubbard insulator – e-e correlation ? Zylberstein and Mott, PRB (1975) Pouget et al., PRB (1974), PRL (1975)
Band insulator – structural component ? Goodenough, Phys. Rev. (1960) Wentzcowitch, PRL (1994)
Ultrafast Structural and Electronic Transitions in VOUltrafast Structural and Electronic Transitions in VO22
Synchrotron Beam Slicing - Layout
Optical Measurements of VOOptical Measurements of VO22 I-M Transition I-M Transition
Time scales: structural ~100 fs (Tvib) electronic <1 fs (a/VFermi)
VO2(45 nm)
Si3N4(150 nm)
delaytransmissionreflectivity
pump(800 nm)
probe(tunable)
hv > 0.7 eV
3dπ
EF
> 50% holes
3d||
3d||
hν
MonoclinicRutile
Optical Pumping – excited state
Transient photo-doping - new information compared to adiabatic changes in doping, pressure, temperature, etc.
Cavalleri et al. Phys. Rev. B 70, 161102(R) (2004)
Rini et al Optics Letters 30,1,(2005)
Synchrotron Beam Slicing - LayoutIR Spectroscopy: Bandgap CollapseIR Spectroscopy: Bandgap Collapse
∆α/α
[at 2
00 fs
del
ay]
probe wavelength [µm]
probe energy [eV]
0.8 1.2 1.6
0.71.01.3
0.0
0.1
0.2
0.3
0.4
0.0
0.3λprobe = 0.8 µm
Delay (ps)
0 1 2
0.0
0.3λprobe = 2 µm
High-T PlasmaEdge
Low-T bandgap
∆α/α
∆α/α
λpump = 800 nm
Rini et al Optics Letters 30,1,(2005)
Synchrotron Beam Slicing - LayoutMott-Hubbard or Band-like?Mott-Hubbard or Band-like?
What causes the formation of the metallic state?What causes the formation of the metallic state?
Mott-Hubbard insulator: e-e correlation
Prompt collapse of the bandgap
Band-like insulator: change of symmetry
Structurally driven transition
Synchrotron Beam Slicing - LayoutPump-probe for different pulse durationsPump-probe for different pulse durations
101 102 103101
102
103
FWHM pulse width (fs)
Tra
nsi
tio
n t
ime
(fs)
Delay (fs) Delay (fs) Delay (fs)0 200
-0.1
0.015 fs
75 fs0 200
122 fs
125 fs
0 500 1000
454 fs
400 fs
∆ R /
R
Electronic response time
Structural BottleneckStructural Bottleneck
λpump, λprobe = 790 nm
Cavalleri et al. Phys. Rev. B 70, 161102 (2004)
Question: is the system metallic immediately after photo-doping?
Answer: The phase transition timescale is 80 fs, also for 10-fs photo-doping
Synchrotron Beam Slicing - LayoutNEXAFS: Band Selective SpectroscopyNEXAFS: Band Selective Spectroscopy
5 1 0 5 2 0 5 3 0 5 4 0
0 .0 0
0 .0 1
0 .0 2
α (n
m
-1 )
V 2 p3 /2 O 1 sV 2 p1 /2
O 1 s
3 dπ
3 dσ3 d//
V 2 p3 /2
V 2 p1 /2
E n e rg y (e V )
5 1 6 e V
5 3 0 e V
α [n
m-1]
Synchrotron Beam Slicing - Layout
ALS Beamline 5.3.1
VO2
synchrotron(~200 fs)
laser(75 fs)
Ruled GratingSpectrometer CCD
Femtosecond NEXAFS Measurements in VOFemtosecond NEXAFS Measurements in VO22
-4000.0 -2000.0 0.0 2000.0 4000.00.4
0.8
1.2
-4000.0 -2000.0 0.0 2000.0 4000.00.40
0.80
1.20
V 2p
O 1s~2 eV
<0.5 eV valency change ⇒ chemical edge shift
O2- ⇒ O2.25- V4+ ⇒ V4.5+
2p
3d// 3dπ
EF
3dσ
(1) (2) (3)
2p 2p3d//
3dπ
3d// 3d//
3dπ
photo-doped insulator metal Tel>>Tl metal Tel=Tl
E-EF
fE
E-EF
fE
A.Cavalleri et al., Phys. Rev. Lett., 95, 067405, (2005).
Delay (ps)2 40-2
∆T/T
(516
eV
)∆T
/T (5
31 e
V)
1
0.8
0.6
1
0.8
0.6
V 2p3/2 edge - dynamics in V-d bands
O1s edge - dynamics in O-p bands
hole doping
e-doping
516 eV
530 eV
Delay (ps)-2 0 2 4
Synchrotron Beam Slicing - Layout
ALS Beamline 5.3.1
VO2
synchrotron(~200 fs)
laser(75 fs)
Ruled GratingSpectrometer CCD
Femtosecond NEXAFS Measurements in VOFemtosecond NEXAFS Measurements in VO22
-4000.0 -2000.0 0.0 2000.0 4000.00.4
0.8
1.2
-4000.0 -2000.0 0.0 2000.0 4000.00.40
0.80
1.20
V 2p
O 1s~2 eVO2- ⇒ O2.25- V4+ ⇒ V4.5+
2p
3d// 3dπ
EF
3dσ
(1) (2) (3)
2p 2p3d//
3dπ
3d// 3d//
3dπ
photo-doped insulator metal Tel>>Tl metal Tel=Tl
<0.5 eV valency change ⇒ chemical edge shift
E-EF
fE
E-EF
fE
A.Cavalleri et al., Phys. Rev. Lett., 95, 067405, (2005).
Delay (ps)2 40-2
∆T/T
(516
eV
)∆T
/T (5
31 e
V)
1
0.8
0.6
1
0.8
0.6
V 2p3/2 edge - dynamics in V-d bands
O1s edge - dynamics in O-p bands
hole doping
e-doping
516 eV
530 eV
Synchrotron Beam Slicing - Layout
ALS Beamline 5.3.1
VO2
synchrotron(~200 fs)
laser(75 fs)
Ruled GratingSpectrometer CCD
Femtosecond NEXAFS Measurements in VOFemtosecond NEXAFS Measurements in VO22
-4000.0 -2000.0 0.0 2000.0 4000.00.4
0.8
1.2
-4000.0 -2000.0 0.0 2000.0 4000.00.40
0.80
1.20
2p
3d// 3dπ
EF
3dσ
(1) (2) (3)
2p 2p3d//
3dπ
3d// 3d//
3dπ
photo-doped insulator metal Tel>>Tl metal Tel=Tl
V 2p
O 1s~2 eV
<0.5 eV valency change ⇒ chemical edge shift
O2- ⇒ O2.25- V4+ ⇒ V4.5+
E-EF
fE
E-EF
fE
A.Cavalleri et al., Phys. Rev. Lett., 95, 067405, (2005).
Delay (ps)2 40-2
∆T/T
(516
eV
)∆T
/T (5
31 e
V)
1
0.8
0.6
1
0.8
0.6
V 2p3/2 edge - dynamics in V-d bands
O1s edge - dynamics in O-p bands
hole doping
e-doping
516 eV
530 eV
Synchrotron Beam Slicing - Layout
Ef
Photo-doping
(1) Insulating phaseTelectr >> Tlatt
(2) Metallic phaseTelectr = Tlatt
(3) Metallic phase
O1s
V2p
O1s
V2p
O1s
V2p
3d//
3d//
3dπ
3d//
3dπ
3d//
3dπ
fe
E-Ef
fe
E-Ef
Valency Change: Dynamic Chemical ShiftValency Change: Dynamic Chemical Shift
Synchrotron Beam Slicing - Layout
bendmagnet
mirror x-rays
electron-photon interaction in wiggler
e-beam
femtosecond electron bunch
30 ps electronbunch
femtosecondlaser pulse
femtosecond x-rays
Zholents and Zolotorev, Phys. Rev. Lett., 76, 916,(1996).
Tunable femtosecond X-rays at the ALSTunable femtosecond X-rays at the ALS
Schoenlein et al., Science, 287, (2000)
laserwiggler
λW
wiggler
Synchrotron Beam Slicing - Layout
bendmagnet
mirror x-rays
electron-photon interaction in wiggler
e-beam
femtosecond electron bunch
30 ps electronbunch
femtosecondlaser pulse
femtosecond x-rays
Upcoming Undulator BeamlineUpcoming Undulator Beamline
20 KHz laserwiggler
λW
wiggler
Undulator
Synchrotron Beam Slicing - Layout
Femtosecond X-ray FluxFemtosecond X-ray Flux
HHG flux from F. Krausz, laser: 10 fs, 3 mJ/pulse, 30 W
Plasma source flux in mrad2 laser: 40 fs, 1 mJ/pulse, 30 W (continuum includes projected 105 improvement)
103 104
104
105
106
107
108
photon energy (eV)
flux
(ph/
s/0.
1% B
W)
bend magnet flux (150 fs, 1 kHz)
undulator flux (200 fs, 20 kHz)(3 cm period, 1.5 m length, Bmax= 1.5 T)
HHG
plasma Kα
fs plasma continuum
ALS typical average x-ray fluxundulator ~1015 ph/s/0.1% BWbend-magnet ~1013 ph/s/0.1% BW
Cu Kα - 1010 ph/s/4π (proj. 1012 with Hg target)cont. 6x107 ph/s/4π (integ. from 7-8 keV)
300
Synchrotron Beam Slicing - LayoutPhonon-Polaritons in LiTaOPhonon-Polaritons in LiTaO33
Stevens et al, Science 291 (2001) 627
Synchrotron Beam Slicing - LayoutExcitation of Coherent Phonon-polaritonsExcitation of Coherent Phonon-polaritons
κ
ω2
ω1
ω2 − ω1
Cherenkov RadiationDifference Frequency
Austen et al., PRL (1984)
Synchrotron Beam Slicing - LayoutUltrafast X-ray DiffractionUltrafast X-ray Diffraction
e-beam
fs laser
bend magnet
wiggler
femtosecond electron bunch
mirror
femtosecond x-rays
800-nm sampleexcitation pulse
slit
Time delay
detector
(006) LiTaO3
Monochromator
Synchrotron Beam Slicing - LayoutTime-resolved 006 Structure FactorTime-resolved 006 Structure Factor
- 1 0 0 0 0 1 0 0 0 2 0 0 0
1 . 0 0
1 . 0 1
F i t : ν = 1 . 4 T H z + / - 0 . 1 γ = 1 . 8 p s
(00
6 S
tru
ctu
re
fa
cto
r)
2
Synchrotron Beam Slicing - LayoutOptical Exp: time-resolved Pockels effectOptical Exp: time-resolved Pockels effect
Front view
Optical Probe
Optical Pump
Synchrotron Beam Slicing - LayoutTime-resolved Pockels effectTime-resolved Pockels effect
0 2 0 0 0 4 0 0 0D e la y ( f s )
0 2 0 0 0 4 0 0 0
- 1 2
- 8
- 4
0
DT
/T (
%)
0 2 4 6 8
fre q u e n c y [T H z ]
A1 T O (2 0 5 c m-1)
6 .1 6 T H z
2 .2 T H z
2 0 0 0 4 0 0 0
D e la y (fs )
∆T/T
Synchrotron Beam Slicing - Layout
0 2 4 6 8
fre q u e n c y [T H z ]
A1 T O (2 0 5 c m-1)
6 .1 6 T H z
2 .2 T H z
2 0 0 0 4 0 0 0
D e la y (fs )
Comparison with Optical dataComparison with Optical data
X-rays
Nyquist Limit for 150 fs x-rays
6.2 THz A1g TO phonon
Synchrotron Beam Slicing - LayoutTa-O displacement along the c axisTa-O displacement along the c axis
- 1 0 0 0 0 1 0 0 0 2 0 0 0
- 2 .0
0 .0
2 .0
d e la y ( p s )
c-a
xis
Ta
-O m
oti
on
(m
A)
Synchrotron Beam Slicing - LayoutFeFeIIII Spin-Crossover Molecules Spin-Crossover Molecules
hν
low spin high spin
• ~10-15% increase in metal-ligand bond distances• trigonal cage distortion?
• electron transfer mechanistic role in biochemical processes (cytochrome P450)
• magnetic and optical storage material
Motivation:• relationship between structure, electronic, and magnetic properties Do the structural distortions facilitate the spin-crossover reaction?
hν
high-spin state
MLCT(charge-transfer state)
low-spin state
τ~700 fs
1A1g
5T2g
∆S=2
(t2g)6 (t2g)4 (eg)2
Fe[tren(py)3]2+
Fe Fe
N
N
N
N
N
NN
N
Synchrotron Beam Slicing - Layout∆µ
x10
-3
energy (eV)
FeFeIIII Time-resolved XAS Time-resolved XAS
τ = 330 ps
eV
XAS at τ = 0 ps(low spin)
X 0.1
(ALS Beamline 5.3.1)
M. Khalil et al., J. Phys. Chem. (in press)
a
bc
a’ b’ c’
330 ps delay
Synchrotron Beam Slicing - LayoutFs X-ray Diffraction and Absorption at the ALSFs X-ray Diffraction and Absorption at the ALS
VO2 Insulator-metal Transition
3d //
V2p 3/2
V2p 1/2
O1s
3d π
3d σ
Femtosecond X-ray AbsorptionPhonon Polaritons in LiTaO3
Femtosecond X-ray Diffraction
- 1 0 0 0 0 1 0 0 0 2 0 0 0
- 2 .0
0 .0
2 .0
d e la y ( p s )
c-a
xis
Ta
-O m
oti
on
(m
A)
7 KeV
006 reflection
531 eV
516 eV4.10-3
6.10-3
8.10-3
-2000 0 2000 40008.10-3
1.10-2
1.2.10-2
Delay (fs)
V 2p3/2 edge - dynamics in d bands
O1s edge - dynamics in π bandsSpin-crossover phase transition
Picosecond X-ray Absorption
∆µ x
10-3
delay (ps)
Eo = 7140 eV
Synchrotron Beam Slicing - LayoutPerovskite ManganitesPerovskite Manganites
O2-
Mn3+
1s2 2s2 2p4[Ar] 3d5 4s2
Re1-xAxMn O3
Re or A
Mn
O
t2g
eg
Synchrotron Beam Slicing - LayoutTwo competing statesTwo competing states
Metallic Insulating
Mn3+ Mn4+ Mn3+ Mn3+ Mn4+ Mn3+
H
FPhase competitionDelicate balance
Electron-delocalizing double-exchange
Charge-localizingreal-space ordering
Synchrotron Beam Slicing - LayoutLattice Effects?Lattice Effects?
t2g
eg
Synchrotron Beam Slicing - Layout
Y. Tomioka et al. Phys Rev. B 53 R1689 (1996)
Pr(1-x)Cax MnO3 : Statically Distorted
O2-
Not quite cubic
Z(Pr)=59
Z(Ca)=20
Doping (x)
Tem
per
atu
re
Always Insulatingfor zero field
Synchrotron Beam Slicing - Layout
Y. Tomioka et al. Phys Rev. B 53 R1689 (1996)
CMR in Pr(1-x)Cax MnO3
Always Insulating at 0 fielddR/dT < 0
FHidden metallicphase
CMR
Synchrotron Beam Slicing - Layout
Colossal Photo-resistance: Colossal Photo-resistance: Pr(1-x)Cax MnO3
Colossal photo-resistance
O2-
Fiebig et al. Science 280, 1925 (1998)
Light
timescale: ~ 230 fs
Synchrotron Beam Slicing - Layout
X-ray Induced IMT: X-ray Induced IMT: Pr(1-x)Cax MnO3
Colossal photo-resistance
O2-
Kiryiukin et al. Nature 386, 813 (1997)
X-rays
Synchrotron Beam Slicing - LayoutCoherent Vibrational ExcitationCoherent Vibrational Excitation
Atomic motion in the electronic ground state
Phase Transitions Occur in the Electronic Ground State
Mid-IR Pulse Raman effect
?
Synchrotron Beam Slicing - LayoutVibrational Excitation ExperimentsVibrational Excitation Experiments
Mn-O Excitation: electronicground state
Mid-IR
Ab
sorp
tio
n
Photon Energy
Synchrotron Beam Slicing - LayoutChange in Phase?Change in Phase?
17.5 µm
800 nm0 5 10
Delay (ps)
-DR
/R @
80
0 n
m
pump
probe
Synchrotron Beam Slicing - LayoutVibrational Excitation ExperimentsVibrational Excitation Experiments
Maximum response by pumping at 16.5 µm
mid IR
0 4 0 0 8 0 0
0 .0 0
0 .0 4
0 .0 8
0 .1 2
0 .1 6
D e la y ( f s )
1 9 .5 µm
1 7 .5 µm
1 7 .5 µm1 6 .5 µm1 4 .5 µm1 2 .5 µm1 0 .5 µm
-DR
/R @
80
0 n
m
pump
800 nmprobe
Synchrotron Beam Slicing - Layoutp e a k
1 p s
0 .0 6 0 .0 8 0 .1 0
-DR
/R @
80
0 n
m
P u m p E n e r g y ( m e V )
Vibrational ExcitationVibrational Excitation
bandgap
Photon Energy
Ab
sorp
tio
n
phonons
Synchrotron Beam Slicing - LayoutWhat is the long-lived state?What is the long-lived state?
0 5 10
Delay (ps)
-DR
/R @
80
0 n
m
Is this anew phase ?
Synchrotron Beam Slicing - LayoutNext Step: probe quasi-DC conductivityNext Step: probe quasi-DC conductivity
mid IR
Gold contacts
Gold contactsI
Synchrotron Beam Slicing - LayoutNecessary: sub-vibrational probingNecessary: sub-vibrational probing
mid IR
10-fs probing
Can you do this in CuO2 - High Tc ?
Can we drive spin-crossover in Co oxides?
Can we coherentlycontrol the phaseof a solid in the Electronic ground state?
Synchrotron Beam Slicing - LayoutFuture Experiments – Vibrational ExcitationFuture Experiments – Vibrational Excitation
Are we driving a first-order phase transition?
Measuring persistent changes in the sample conductivity
Time-resolved THz/Visible probing of the formation of the
metallic phase
Time-resolved X-ray experiments:
Resonant x-ray diffraction: role of charge/orbital ordering
XANES: investigate Mn-O complex, Mn-3d hybridization with
O-2p states
Synchrotron Beam Slicing - LayoutFuture Experiments – Excited Electronic StateFuture Experiments – Excited Electronic State
Origin of the photoinduced phase transition:
melting of the charge-ordering by photoexcited carriers?
Resonant fs x-ray diffraction at the Mn K-absorption edge
Resonant x-ray diffraction is an effective probe of charge and orbital ordering in manganites
Zimmerman et al., Phys. Rev. Lett (1999)
Synchrotron Beam Slicing - LayoutFuture Experiments – Excited Electronic StateFuture Experiments – Excited Electronic State
Valence and conduction bands in CMR manganites are comprised of hybridized Mn-3d and O-2p states
time-resolved XANES at the O K-edge and Mn LII,III-edge
Measuring local structural distortion of the Mn-O complex resulting from the photo-excitation:
•Polaron effects•Ionization of the Jahn-Teller instability•Changes of the Mn-O-Mn bond angle (influencing the double-exchange mechanism)
Synchrotron Beam Slicing - LayoutOxygen K-edgeOxygen K-edge
2p character hybridized with 3d
2p character hybridized with 4sp
Sensitivity to changes in the hybridization for unoccupied states of mixed O-2p and metal-3d character
Subias et al., Surf. Rev. Lett (2002)
Synchrotron Beam Slicing - LayoutO K-edge, Mn L-edgeO K-edge, Mn L-edge
Sensitivity to the rare-earth cation
Sensitivity to the doping ratio
De Groot et al., Phys. Rev. B (1989)
O K-edge
O K-edge
Mn L-edge
Lee et al., Phys. Stat. Sol. A (2003)
Mn L-edge XANES: probes unoccupied states of metal-3d characterChemical shift: changes in the Mn oxidation state
Synchrotron Beam Slicing - Layout
M. Khalil (Fe II)M. Khalil (Fe II)
A. CavalleriA. Cavalleri
R.W. SchoenleinR.W. SchoenleinMaterials Sciences LBNL
Topics and People Topics and People
I-M Transition in VO2
S. Fourmaux, J.C. KiefferS. Fourmaux, J.C. KiefferUniversite’ du Quebec
R. Lopez, R. HaglundR. Lopez, R. HaglundVanderbilt University
T. DekorsyT. DekorsyUniv. Konstanz
Fs NEXAFS
Fs XRD in LiTaO3
K.A. NelsonK.A. NelsonMIT
J. Itatani, S. KoshiharaJ. Itatani, S. KoshiharaKEK and Tokyo Tech.
Y. Tomioka, Y. TokuraY. Tomioka, Y. TokuraUniversity of Tokyo
Vibrational Excitation in CMR