1. Young-June Kim Department of Physics University of Toronto Resonant Inelastic X-ray Scattering Investigation of Cuprates

2. 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

3. NSLS-II Workshop Feb 2008 Young-June Kim Experimental Setup overall energy resolution: ~130 meV (FWHM) 9ID Advanced Photon Source Si(111) Si(444) channel-cut Analyzer Ge(733) Detector Sample

4. NSLS-II Workshop Feb 2008 Young-June Kim MERIX spectrometer credit: Yuri Shvydko

5. NSLS-II Workshop Feb 2008 Young-June Kim Incident energy dependence La 2 CuO 4 Brillouin zone center

6. NSLS-II Workshop Feb 2008 Young-June Kim Third order theory Collapse onto a single curve Abbamonte et al. 1999

7. NSLS-II Workshop Feb 2008 Young-June Kim E i -independent spectrum Dielectric loss function from ellipsometry EELS Theory (van den Brink and van Veenendaal)

8. NSLS-II Workshop Feb 2008 Young-June Kim E i -independent spectrum Dielectric loss function from ellipsometry EELS Theory (van den Brink and van Veenendaal) S(q=0,  ) ~

9. NSLS-II Workshop Feb 2008 Young-June Kim How about other cuprates?

10. NSLS-II Workshop Feb 2008 Young-June Kim La 2 CuO 4 Momentum dependence q Q Ellis et al. PRB in pressKim et al. PRB 2007

11. NSLS-II Workshop Feb 2008 Young-June Kim Comparison with L and M edges M 2,3 -edge (Kuiper et al. 1998) L 3 -edge (Ghiringelli et al. 2004)

12. NSLS-II Workshop Feb 2008 Young-June Kim dd excitation using hard X-ray Going to very large Q Using quadrupole transition as an intermediate state Larson et al., PRL 2007 Sr 2 CuO 3 - Seo et al., PRB 2006

13. NSLS-II Workshop Feb 2008 Young-June Kim d-d excitation in Sr 2 CuO 2 Cl 2 pre-edge (quadrupole) intermediate state

14. NSLS-II Workshop Feb 2008 Young-June Kim Magnetic Excitation? La 2 CuO 4 on-resonance off-resonance  Hill et al. PRL in press

15. NSLS-II Workshop Feb 2008 Young-June Kim Doping Momentum

16. NSLS-II Workshop Feb 2008 Young-June Kim Possibilities? Two magnon excitation Donkov+Chubukov PRB 2007 Vernay et al. PRB 2007

17. NSLS-II Workshop Feb 2008 Young-June Kim More possibilities? Charge 2e boson (Choy, Leigh, and P. Phillips) What about d-d excitation? d(3z 2 -r 2 ) to d(x 2 -y 2 ) is not experimentally identified yet in cuprates But…  t Im[1/  (q,  )]

18. 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

19. NSLS-II Workshop Feb 2008 Young-June Kim Old instrumentation (1m) New instrumentation (2m)

20. 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

21. 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 La 2-x Sr x CuO 4  two magnon? Future: Fermi surface probe? Needs energy resolution improvement ~1.8 eV For La 2 CuO 4 ~2.2 eV ~0.3 eV ~0.5 eV

22. 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)