Quasi-particle interference of heavy fermions in resonant x-ray scattering

András Gyenis; Eduardo H da Silva Neto; Ronny Sutarto; Enrico Schierle; Feizhou He; Eugen Weschke; Mariam Kavai; Ryan E Baumbach; Joe D Thompson; Eric D Bauer; Zachary Fisk; Andrea Damascelli; Ali Yazdani; Pegor Aynajian

doi:10.1126/sciadv.1601086

Quasi-particle interference of heavy fermions in resonant x-ray scattering

Sci Adv. 2016 Oct 14;2(10):e1601086. doi: 10.1126/sciadv.1601086. eCollection 2016 Oct.

Authors

Affiliations

¹ Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA.
² Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.; Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.; Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.; Quantum Materials Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada.
³ Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada.
⁴ Helmholtz-Zentrum Berlin fürMaterialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
⁵ Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY 13902, USA.
⁶ Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
⁷ Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA.
⁸ Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.; Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.

Abstract

Resonant x-ray scattering (RXS) has recently become an increasingly important tool for the study of ordering phenomena in correlated electron systems. Yet, the interpretation of RXS experiments remains theoretically challenging because of the complexity of the RXS cross section. Central to this debate is the recent proposal that impurity-induced Friedel oscillations, akin to quasi-particle interference signals observed with a scanning tunneling microscope (STM), can lead to scattering peaks in RXS experiments. The possibility that quasi-particle properties can be probed in RXS measurements opens up a new avenue to study the bulk band structure of materials with the orbital and element selectivity provided by RXS. We test these ideas by combining RXS and STM measurements of the heavy fermion compound CeMIn₅ (M = Co, Rh). Temperature- and doping-dependent RXS measurements at the Ce-M₄ edge show a broad scattering enhancement that correlates with the appearance of heavy f-electron bands in these compounds. The scattering enhancement is consistent with the measured quasi-particle interference signal in the STM measurements, indicating that the quasi-particle interference can be probed through the momentum distribution of RXS signals. Overall, our experiments demonstrate new opportunities for studies of correlated electronic systems using the RXS technique.

Keywords: Resonant x-ray scattering (RXS); heavy fermions; quasiparticle interference; scanning tunneling microscopy (STM); strongly correlated electron systems.