Field-Angle-Resolved Specific Heat in Na_{2}Co_{2}TeO_{6}: Evidence against Kitaev Quantum Spin Liquid.

Authors

Shengjie Fang, Kumpei Imamura, Yuta Mizukami, Ryuichi Namba, Kota Ishihara, Kenichiro Hashimoto, Takasada Shibauchi

Published in

Physical review letters. Volume 134. Issue 10. Pages 106701. Mar 14, 2025.

Abstract

Kitaev quantum spin liquids (KSLs) in layered honeycomb magnets are known to host Majorana quasiparticles, whose excitations depend strongly on the direction of the applied magnetic field. In the high-field phase of α-RuCl_{3}, specific heat measurements have revealed characteristic field-angle dependence of low-energy excitations consistent with the Kitaev model, providing bulk evidence for the KSL state. Here we present low-temperature measurements of specific heat C(T) for another KSL candidate Na_{2}Co_{2}TeO_{6} (NCTO) under field rotation within the honeycomb plane. Above the critical field of antiferromagnetic order, the field-angle dependence of C/T exhibits minima along the bond directions, contrasting with the maxima observed in the KSL state of α-RuCl_{3}. Our analysis indicates nodeless, fully gapped excitations, which are inconsistent with the angle-dependent Majorana excitations with gapless nodes predicted by the Kitaev model. These findings suggest that low-energy excitations in NCTO are governed by gapped magnon excitations rather than Majorana quasiparticles, providing thermodynamic evidence against a KSL state.

PMID:
40153638
Bibliographic data and abstract were imported from PubMed on 29 Mar 2025.

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