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Resonant Inelastic X-ray Scattering Investigation of Cuprates. Young-June Kim Department of Physics University of Toronto. Outline. Resonant IXS What is indirect RIXS? Considering outgoing resonance response function? but there is more Charge transfer excitation (> 2 eV)
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Resonant Inelastic X-ray Scattering Investigation of Cuprates Young-June Kim Department of Physics University of Toronto
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
Analyzer Ge(733) Si(111) Detector Sample Si(444) channel-cut Experimental Setup 9ID Advanced Photon Source overall energy resolution: ~130 meV (FWHM)
MERIX spectrometer credit: Yuri Shvydko
Incident energy dependence La2CuO4 Brillouin zone center
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)
~ S(q=0,w) Ei-independent spectrum • Dielectric loss function from • ellipsometry • EELS • Theory (van den Brink and van Veenendaal)
La2CuO4 Momentum dependence Q q Ellis et al. PRB in press Kim et al. PRB 2007
Comparison with L and M edges M2,3-edge (Kuiper et al. 1998) L3-edge (Ghiringelli et al. 2004)
dd excitation using hard X-ray Larson et al., PRL 2007 • Going to very large Q • Using quadrupole transition as an intermediate state Sr2CuO3 - Seo et al., PRB 2006
d-d excitation in Sr2CuO2Cl2 • pre-edge (quadrupole) intermediate state
La2CuO4 (p, 0) on-resonance off-resonance Magnetic Excitation? Hill et al. PRL in press
Momentum Doping
Vernay et al. PRB 2007 Donkov+Chubukov PRB 2007 Possibilities? • Two magnon excitation
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… Im[1/e(q,w)] w/t
Cvetkovic et al., cond-mat/0607402 Lee and Nagaosa, PRB 2003 Perhaps in the future? 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 (p, 0) In La2-xSrxCuO4 two magnon? • Future: • Fermi surface probe? • Needs energy resolution improvement For La2CuO4 ~1.8 eV ~2.2 eV ~0.3 eV ~0.5 eV
Thanks to • 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) • Toronto • Jung Ho Kim • David Ellis • John P. Hill (BNL) • Girsh Blumberg (Lucent)