Resonant Inelastic X-ray Scattering Investigation of Cuprates

Young-June KimDepartment of PhysicsUniversity of Toronto

Resonant Inelastic X-ray Scattering

Investigation of Cuprates

NSLS-II Workshop Feb 2008 Young-June Kim

Outline Resonant IXS

What is indirect RIXS? Considering outgoing resonance response function? but there is more

Charge transfer excitation (> 2 eV) Orbital selective d-d excitation (< 2eV) Multi-magnon excitation (< 1eV) Conclusions and Outlook


Experimental Setup

overall energy resolution: ~130 meV (FWHM)

9IDAdvanced

Photon Source

Si(111)

Si(444) channel-cut

Analyzer Ge(733)

Detector

Sample


MERIX spectrometer

credit: Yuri Shvydko


Incident energy dependenceLa2CuO4 Brillouin zone center

)))(()(()()(~

)( 2222mminns

ifKK EE

EESI


Third order theory

Collapse onto a single curve

Abbamonte et al. 1999


Ei-independent spectrum

Dielectric loss function from ellipsometry EELS

Theory (van den Brink and van Veenendaal)

2 4 6 8 10

0

3

0.0

0.2

(eV)

b

)(1Im),0(

QS


Ei-independent spectrum

Dielectric loss function from ellipsometry EELS

Theory (van den Brink and van Veenendaal)

2 4 6 8 10

0

3

0.0

0.2

(eV)

b

)(1Im),0(

qS

S(q=

0,

)~


How about other cuprates?


La2CuO4

Momentum dependence GqQ

qQ

Ellis et al. PRB in press Kim et al. PRB 2007

NSLS-II Workshop Feb 2008 Young-June KimComparison with L and M edges

M2,3-edge (Kuiper et al. 1998) L3-edge (Ghiringelli et al. 2004)

NSLS-II Workshop Feb 2008 Young-June Kimdd excitation using hard X-ray

Going to very large Q

Using quadrupole transition as an intermediate state

Larson et al., PRL 2007

Sr2CuO3 - Seo et al., PRB 2006


d-d excitation in Sr2CuO2Cl2

pre-edge (quadrupole) intermediate state


Magnetic Excitation?

La2CuO4

on-resonance

off-resonance

Hill et al. PRL in press


Doping Momentum


Possibilities? Two magnon excitation

Donkov+ChubukovPRB 2007

Vernay et al. PRB 2007


More possibilities? Charge 2e boson (Choy, Leigh, and P. Phillips)

What about d-d excitation? d(3z2-r2) to d(x2-y2) is not experimentally

identified yet in cuprates But…

t

Im[1

/(q

,)]


Perhaps in the future?Cvetkovic et al., cond-mat/0607402

Lee and Nagaosa, PRB 2003

CeB6, Zirngiebl et al. PRB 1984


Old instrumentation (1m)

New instrumentation (2m)


NSLS-II wish list Improved energy resolution

10-20 meV resolution will allow us to study excitations in the 50-100 meV range

Pseudo gap in high Tc superconductors Magnetic excitation Crystal field in Rare-earths Magnon-phonon-electron interaction

Smaller beam size (20 nm?) Scanning IXS? Probing electronic structure in inhomogeneous

sample


Conclusion and Outlook Resonant Inelastic X-ray Scattering can

probe d-d orbital excitations Charge-transfer gap Dispersion bandwidth Perhaps magnetic excitation

Needs more work Mid-IR excitation at (, 0) In La2-xSrxCuO4

two magnon? Future:

Fermi surface probe? Needs energy resolution improvement

~1.8 eV

For La2CuO4

~2.2 eV

~0.3 eV

~0.5 eV


Thanks to Toronto

Jung Ho Kim

David Ellis

John P. Hill (BNL) Girsh Blumberg (Lucent)

APS XOR T. Gog D. Casa Y. Shvydko

Samples N. Motoyama, K. M. Kojima, and

S. Uchida (U. Tokyo) F. C. Chou (MIT) S. Wakimoto (JAEA) G. Gu, M. Huecker (BNL) S. Komiya, Y. Ando (CRIEPI) H. Zhang (Toronto)

Resonant Inelastic X-ray Scattering Investigation of Cuprates

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