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

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Main Authors: Arneth, J., Choi, K. -Y., Kalaivanan, R., Sankar, R., Klingeler, R.
Format: Preprint
Published: 2024
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author Arneth, J.
Choi, K. -Y.
Kalaivanan, R.
Sankar, R.
Klingeler, R.
author_facet Arneth, J.
Choi, K. -Y.
Kalaivanan, R.
Sankar, R.
Klingeler, R.
contents 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 $α_c$ 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.
format Preprint
id arxiv_https___arxiv_org_abs_2409_05661
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Signatures of a Quantum Critical Endpoint in the Kitaev Candidate Na$_2$Co$_2$TeO$_6$
Arneth, J.
Choi, K. -Y.
Kalaivanan, R.
Sankar, R.
Klingeler, R.
Strongly Correlated Electrons
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 $α_c$ 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.
title Signatures of a Quantum Critical Endpoint in the Kitaev Candidate Na$_2$Co$_2$TeO$_6$
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2409.05661