Upper-branch thermal Hall effect in quantum paramagnets

Inspired by the persistent thermal Hall effects at finite temperatures in various quantum paramagnets, we explore the origin of the thermal Hall effects from the perspective of the upper branch parts by invoking dispersive and twisted crystal field excitations. It is shown that the upper branches of...

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Main Authors: Bowen Ma, Z. D. Wang, Gang V. Chen
Format: Article
Language:English
Published: American Physical Society 2024-04-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.6.023044
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author Bowen Ma
Z. D. Wang
Gang V. Chen
author_facet Bowen Ma
Z. D. Wang
Gang V. Chen
author_sort Bowen Ma
collection DOAJ
description Inspired by the persistent thermal Hall effects at finite temperatures in various quantum paramagnets, we explore the origin of the thermal Hall effects from the perspective of the upper branch parts by invoking dispersive and twisted crystal field excitations. It is shown that the upper branches of the local energy levels could hybridize and form dispersive bands. The observation is that, upon time-reversal symmetry breaking by the magnetic fields, these upper branch bands could acquire a Berry curvature distribution and contribute to the thermal Hall effect even in the paramagnetic regime. As a proof of principle, we consider the setting on kagomé lattice with one ground-state singlet and an excited doublet, and show this is indeed possible. We expect this effect to be universal and that it has no strong connection with the underlying lattice. Although the thermal Hall signal can be contributed from other sources such as phonons and their scattering in the actual materials, we discuss the application to the relevant quantum materials.
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spelling doaj.art-dda19964d22b49bab02c00c2926675fb2024-04-12T17:41:27ZengAmerican Physical SocietyPhysical Review Research2643-15642024-04-016202304410.1103/PhysRevResearch.6.023044Upper-branch thermal Hall effect in quantum paramagnetsBowen MaZ. D. WangGang V. ChenInspired by the persistent thermal Hall effects at finite temperatures in various quantum paramagnets, we explore the origin of the thermal Hall effects from the perspective of the upper branch parts by invoking dispersive and twisted crystal field excitations. It is shown that the upper branches of the local energy levels could hybridize and form dispersive bands. The observation is that, upon time-reversal symmetry breaking by the magnetic fields, these upper branch bands could acquire a Berry curvature distribution and contribute to the thermal Hall effect even in the paramagnetic regime. As a proof of principle, we consider the setting on kagomé lattice with one ground-state singlet and an excited doublet, and show this is indeed possible. We expect this effect to be universal and that it has no strong connection with the underlying lattice. Although the thermal Hall signal can be contributed from other sources such as phonons and their scattering in the actual materials, we discuss the application to the relevant quantum materials.http://doi.org/10.1103/PhysRevResearch.6.023044
spellingShingle Bowen Ma
Z. D. Wang
Gang V. Chen
Upper-branch thermal Hall effect in quantum paramagnets
Physical Review Research
title Upper-branch thermal Hall effect in quantum paramagnets
title_full Upper-branch thermal Hall effect in quantum paramagnets
title_fullStr Upper-branch thermal Hall effect in quantum paramagnets
title_full_unstemmed Upper-branch thermal Hall effect in quantum paramagnets
title_short Upper-branch thermal Hall effect in quantum paramagnets
title_sort upper branch thermal hall effect in quantum paramagnets
url http://doi.org/10.1103/PhysRevResearch.6.023044
work_keys_str_mv AT bowenma upperbranchthermalhalleffectinquantumparamagnets
AT zdwang upperbranchthermalhalleffectinquantumparamagnets
AT gangvchen upperbranchthermalhalleffectinquantumparamagnets