Electronic and magnetic properties of the RuX3 (X = Cl, Br, I) family: two siblings—and a cousin?

• Published in: npj quantum materials Vol. 7; no. 1; pp. 1 - 9
• Main Authors: Kaib, David A. S., Riedl, Kira, Razpopov, Aleksandar, Li, Ying, Backes, Steffen, Mazin, Igor I., Valentí, Roser
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29-07-2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/995; 639/766/119/997; Comparative analysis; Condensed Matter Physics; First principles; Frustrated magnetism; Grain boundaries; Heat; Magnetic moments; Magnetic properties; Metallicity; Metals; Physics; Physics and Astronomy; Quantum Physics; Ruthenium trichloride; Siblings; Spin liquid; Structural Materials; Surfaces and Interfaces; Thin Films
• ISSN: 2397-4648; 2397-4648
• DOI: 10.1038/s41535-022-00481-3

Motivated by reports of metallic behavior in the recently synthesized RuI
3
, in contrast to the Mott-insulating nature of the actively discussed
α
-RuCl
3
, as well as RuBr
3
, we present a detailed comparative analysis of the electronic and magnetic properties of this family of trihalides. Using a combination of first-principles calculations and effective-model considerations, we conclude that RuI
3
, similarly to the other two members, is most probably on the verge of a Mott insulator, but with much smaller magnetic moments and strong magnetic frustration. We predict the ideal pristine crystal of RuI
3
to have a nearly vanishing conventional nearest-neighbor Heisenberg interaction and to be a quantum spin liquid candidate of a possibly different kind than the Kitaev spin liquid. In order to understand the apparent contradiction to the reported resistivity
ρ
, we analyze the experimental evidence for all three compounds and propose a scenario for the observed metallicity in existing samples of RuI
3
. Furthermore, for the Mott insulator RuBr
3,
we obtain a magnetic Hamiltonian of a similar form to that in the much-discussed
α
-RuCl
3
and show that this Hamiltonian is in agreement with experimental evidence in RuBr
3
.