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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
NSLS-II Workshop Feb 2008 Young-June Kim
Experimental Setup
overall energy resolution: ~130 meV (FWHM)
9IDAdvanced
Photon Source
Si(111)
Si(444) channel-cut
Analyzer Ge(733)
Detector
Sample
NSLS-II Workshop Feb 2008 Young-June Kim
MERIX spectrometer
credit: Yuri Shvydko
NSLS-II Workshop Feb 2008 Young-June Kim
Incident energy dependenceLa2CuO4 Brillouin zone center
)))(()(()()(~
)( 2222mminns
ifKK EE
EESI
NSLS-II Workshop Feb 2008 Young-June Kim
Third order theory
Collapse onto a single curve
Abbamonte et al. 1999
NSLS-II Workshop Feb 2008 Young-June Kim
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
NSLS-II Workshop Feb 2008 Young-June Kim
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,
)~
NSLS-II Workshop Feb 2008 Young-June Kim
How about other cuprates?
NSLS-II Workshop Feb 2008 Young-June Kim
La2CuO4
Momentum dependence GqQ
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
NSLS-II Workshop Feb 2008 Young-June Kim
d-d excitation in Sr2CuO2Cl2
pre-edge (quadrupole) intermediate state
NSLS-II Workshop Feb 2008 Young-June Kim
Magnetic Excitation?
La2CuO4
on-resonance
off-resonance
Hill et al. PRL in press
NSLS-II Workshop Feb 2008 Young-June Kim
Doping Momentum
NSLS-II Workshop Feb 2008 Young-June Kim
Possibilities? Two magnon excitation
Donkov+ChubukovPRB 2007
Vernay et al. PRB 2007
NSLS-II Workshop Feb 2008 Young-June Kim
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
,)]
NSLS-II Workshop Feb 2008 Young-June Kim
Perhaps in the future?Cvetkovic et al., cond-mat/0607402
Lee and Nagaosa, PRB 2003
CeB6, Zirngiebl et al. PRB 1984
NSLS-II Workshop Feb 2008 Young-June Kim
Old instrumentation (1m)
New instrumentation (2m)
NSLS-II Workshop Feb 2008 Young-June Kim
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
NSLS-II Workshop Feb 2008 Young-June Kim
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
NSLS-II Workshop Feb 2008 Young-June Kim
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)