Ferrimagnetism from triple- q order in Na2Co2TeO6

Research output: Contribution to journalResearch articleContributedpeer-review

Abstract

The candidate Kitaev magnet Na2Co2TeO6 exhibits a characteristic ferrimagnetic response at low temperatures, with a finite residual magnetization that changes sign at a compensation point located at around half the ordering temperature. We argue that the behavior can be naturally understood to arise in this material as a consequence of a noncollinear triple-q magnetic ground state. Using large-scale classical Monte Carlo simulations, we study the finite-temperature response of the pertinent honeycomb Heisenberg-Kitaev-Γ-Γ′ model in weak training fields. Our model features all symmetry-allowed nearest-neighbor exchange interactions, as well as sublattice-dependent next-nearest-neighbor interactions, consistent with the reported crystal structure of the material. We also consider a six-spin ring exchange perturbation, which allows us to tune between the two different magnetic long-range orders that have been suggested for this material in the literature, namely, a collinear single-q zigzag state and a noncollinear triple-q state. We demonstrate that the experimentally observed ferrimagnetic response of Na2Co2TeO6 can be well described within our modeling if the magnetic ground state features noncollinear triple-q order. The observation of a compensation point, where the residual magnetization reverses sign, suggests a sublattice g-factor anisotropy, with a larger out-of-plane g factor on the sublattice with stronger antiferromagnetic intrasublattice exchange. By contrast, a classical Heisenberg-Kitaev-Γ-Γ′-type model with collinear zigzag ground state is insufficient even in principle to describe the observed behavior. Our results illustrate the unconventional physics of noncollinear magnetic long-range orders hosted by frustrated magnets with bond-dependent interactions.

Details

Original languageEnglish
Article number235118
JournalPhysical Review B
Volume110
Issue number23
Early online date6 Dec 2024
Publication statusPublished - 15 Dec 2024
Peer-reviewedYes

External IDs

Scopus 85213713477

Keywords