Femtosecond X-ray studies of strongly correlated electron systems · 2006-01-20 · Electronic Structural Dynamics • charge transfer • correlated electron systems charge/orbital

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


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:


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


Phase of a solidPhase of a solid

Empty band

The “stiffness” of a phase is strongly affected by charge arrangements

Charge ordered band


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


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


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]


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


ALS Beamline 5.3.1

VO2


laser(75 fs)



-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



E-EF

fE

E-EF

fE


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



hole doping

e-doping

516 eV

530 eV


ALS Beamline 5.3.1

VO2


laser(75 fs)



-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


V 2p

O 1s~2 eV


O2- ⇒ O2.25- V4+ ⇒ V4.5+

E-EF

fE

E-EF

fE


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



hole doping

e-doping

516 eV

530 eV


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


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


bendmagnet

mirror x-rays

electron-photon interaction in wiggler

e-beam


30 ps electronbunch

femtosecondlaser pulse

femtosecond x-rays

Upcoming Undulator BeamlineUpcoming Undulator Beamline

20 KHz laserwiggler

λW

wiggler

Undulator


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


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


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


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


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


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


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


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

Femtosecond X-ray studies of strongly correlated electron systems · 2006-01-20 · Electronic Structural Dynamics • charge transfer • correlated electron systems charge/orbital

Documents