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Title: Signatures of non-Loudon-Fleury Raman scattering in the Kitaev magnet β – Li 2 IrO 3

Journal Article · · Physical Review. B
ORCiD logo [1];  [2]; ORCiD logo [3];  [4];  [5]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States)
  2. Boston College, Chestnut Hill, MA (United States)
  3. Loughborough Univ. (United Kingdom)
  4. Univ. of California, San Diego, CA (United States)
  5. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
+ Show Author Affiliations

Here we investigate the magnetic excitations of the hyperhoneycomb Kitaev magnet β-Li2IrO3 by means of inelastic Raman scattering. The spectra exhibit the coexistence of a broad scattering continuum and two sharp low-energy peaks at 2.5 and 3 meV, with a distinctive polarization dependence. While the continuum is suggestive of fractional quasiparticles emerging from a proximate quantum spin liquid phase, the sharp peaks provide the first experimental signature of the "non-Loudon- Fleury" one-magnon scattering processes proposed recently [Yang et al., Phys. Rev. B 104, 144412 (2021)]. The corresponding microscopic mechanism is similar to the one leading to the symmetric off-diagonal exchange interaction Γ (because it involves a combination of both direct and ligand-mediated exchange paths) but is otherwise completely unexpected within the traditional Loudon-Fleury theory of Raman scattering. The present experimental verification therefore calls for a drastic reevaluation of Raman scattering in similar systems with strong spin-orbit coupling and multiple exchange paths.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; US Department of the Navy, Office of Naval Research (ONR); Engineering and Physical Sciences Research Council (EPSRC)
Grant/Contract Number:
AC02-05CH11231; SC0018056; SC0018675
OSTI ID:
1906675
Journal Information:
Physical Review. B, Journal Name: Physical Review. B Journal Issue: 24 Vol. 105; ISSN 2469-9950
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Kitaev model
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