Signatures of a Quantum Critical Endpoint in the Kitaev Candidate Na${}_2$Co${}_2$TeO${}_6$

Abstract

The putative Kitaev material Na${}_2$Co${}_2$TeO${}_6$ has recently been proposed to enter a quantum spin disordered state when magnetic fields are applied in parallel to the honeycomb layers. In this report we uncover signatures of a quantum critical endpoint (QCEP) associated with the assumed order-disorder transition by means of high-resolution capacitance dilatometry. At the critical field $B_{\mathrm{C}}\simeq 6$~T , a sign change of the out-of-plane thermal expansion coefficient ${\alpha }_c$ indicates accumulation of entropy upon crossing the phase boundary. The proportional relationship between isothermal magnetisation and magnetostriction signals that the QCEP can be tuned by magnetic field and pressure simultaneously. The presented results expand the material classes that exhibit metamagnetic quantum criticality to honeycomb antiferromagnets with possible Kitaev interactions.

20 pages, 13 figures, submitted to PRB

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Cited by in corpus (7)

• Ferrimagnetism from triple-q order in Na${}_2$Co${}_2$TeO${}_6$
• Spin waves in Na${}_2$Co${}_2$TeO${}_6$ studied by high-frequency/high-field ESR: Successes and failures of the triple-$\mathbf{q}$ model
• Ferrimagnetism from quantum fluctuations in Kitaev materials
• Competing Interactions and the Effects of Uniaxial Out-of-plane Perturbations in the Honeycomb Antiferromagnet Na${}_2$Co${}_2$TeO${}_6$
• Critical behavior and evidence of dimensional crossover in quasi-two-dimensional Li${}_2$FeSiO${}_4$
• Anisotropic magnetoelastic coupling in the honeycomb magnet Na${}_3$Co${}_2$SbO${}_6$
• Quantum Supercritical Crossover with Dynamical Singularity