Spin and charge excitations in the correlated multiband metal Ca3Ru2O7
[2];
[2];
- Max Planck Institute for Solid State Research, Stuttgart (Germany); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
- Max Planck Institute for Solid State Research, Stuttgart (Germany)
- Inst. Laue-Langevin (ILL), Grenoble (France)
- Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
- Max Planck Institute for Solid State Research, Stuttgart (Germany); Pohang Univ. of Science and Technology (POSTECH) (Korea); Institute for Basic Science (IBS), Pohang (South Korea)
We use Ru $$L_3$$-edge resonant inelastic x-ray scattering to study the full range of excitations in Ca3Ru2O7 from meV-scale magnetic dynamics through to the eV-scale interband transitions. This bilayer 4d-electron correlated metal expresses a rich phase diagram, displaying long-range magnetic order below 56 K followed by a concomitant structural, magnetic, and electronic transition at 48 K. In the low-temperature phase, we observe a magnetic excitation with a bandwidth of ~30 meV and a gap of ~8 meV at the zone center, in excellent agreement with inelastic neutron scattering data. The dispersion can be modeled using a Heisenberg Hamiltonian for a bilayer S = 1 system with single-ion anisotropy terms. At a higher energy loss, dd-type excitations show heavy damping in the presence of itinerant electrons, giving rise to a fluorescencelike signal appearing between the $$t_{2g}$$ and $$e_g$$ bands. At the same time, we observe a resonance originating from localized $$t_{2g}$$ excitations, in analogy to the structurally related Mott insulator Ca2RuO4. But whereas Ca2RuO4 shows sharp separate spin-orbit excitations and Hund’s-rule driven spin-state transitions, here we identify only a single broad asymmetric feature. These results indicate that local intraionic interactions underlie the correlated physics in Ca3Ru2O7, even as the excitations become strongly mixed in the presence of itinerant electrons.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); European Research Council (ERC)
- Grant/Contract Number:
- AC02-76SF00515; 669550
- OSTI ID:
- 1777459
- Journal Information:
- Physical Review B, Vol. 103, Issue 8; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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