Gapped nodal planes and large topological Nernst effect in the chiral lattice antiferromagnet CoNb3S6

The electronic structure of compensated antiferromagnets (CAF) creates large functional responses, reminiscent of ferromagnets and suitable for data storage and readout, despite (nearly) net-zero spontaneous magnetization. Many experimental signatures of CAF - such as giant thermoelectric Nernst effects - should be enhanced when two or more electronic bands are nearly degenerate in vicinity of the Fermi energy. Here, we report a zero-field, thermoelectric Nernst effect >1 μV/K in the CAF CoNb<sub>3</sub>S<sub>6</sub> despite its tiny net magnetization ~2 milli - μ<sub>B</sub>. As drivers of the functional Nernst and Hall effects, we identify near-degeneracies of electron bands at the upper and lower boundaries of the first Brillouin zone, which are vestiges of nodal planes enforced by a screw axis symmetry in the paramagnetic state. Hot spots of emergent, or fictitious, magnetic fields are formed at the slightly gapped nodal planes. Taking into account more than six hundred Wannier orbitals, our theoretical model reproduces the observed spontaneous Nernst effect, emphasizes the role of proximate spin-space group symmetries and nodal planes for the electronic structure of CAF, and demonstrates the promise of ab-initio search for functional responses in a wide class of materials with reconstructed unit cells (supercells) due to spin or charge order.

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Publication Details

Journal
Nature Communications
Published
2025-03-26
DOI
https://doi.org/10.1038/s41467-025-57320-9
Citations
12
Primary Topic
Topological Materials and Phenomena
Type
article
Field-Weighted Citation Impact
14.96

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article

Gapped nodal planes and large topological Nernst effect in the chiral lattice antiferromagnet CoNb3S6

Ming‐Chun Jiang, Takuya Nomoto, Hikaru Watanabe, Yasujiro Taguchi et al.
12 citations
Nature Communications
Topological Materials and Phenomena
14.96
article

Gapped nodal planes and large topological Nernst effect in the chiral lattice antiferromagnet CoNb3S6

Ming‐Chun Jiang, Takuya Nomoto, Hikaru Watanabe, Yasujiro Taguchi, R. Yamada, Yudai Hayashi, Moritz M. Hirschmann, Susumu Minami, Y. Takahashi, Yoshihiro Okamura, Max Hirschberger, N. D. Khanh, Guang‐Yu Guo, Niclas Heinsdorf, Ryotaro Arita, S. Seki, Yoshinori Tokura, Daiki Yamaguchi
article en
12 citations

Abstract

The electronic structure of compensated antiferromagnets (CAF) creates large functional responses, reminiscent of ferromagnets and suitable for data storage and readout, despite (nearly) net-zero spontaneous magnetization. Many experimental signatures of CAF - such as giant thermoelectric Nernst effects - should be enhanced when two or more electronic bands are nearly degenerate in vicinity of the Fermi energy. Here, we report a zero-field, thermoelectric Nernst effect >1 μV/K in the CAF CoNb<sub>3</sub>S<sub>6</sub> despite its tiny net magnetization ~2 milli - μ<sub>B</sub>. As drivers of the functional Nernst and Hall effects, we identify near-degeneracies of electron bands at the upper and lower boundaries of the first Brillouin zone, which are vestiges of nodal planes enforced by a screw axis symmetry in the paramagnetic state. Hot spots of emergent, or fictitious, magnetic fields are formed at the slightly gapped nodal planes. Taking into account more than six hundred Wannier orbitals, our theoretical model reproduces the observed spontaneous Nernst effect, emphasizes the role of proximate spin-space group symmetries and nodal planes for the electronic structure of CAF, and demonstrates the promise of ab-initio search for functional responses in a wide class of materials with reconstructed unit cells (supercells) due to spin or charge order.

Nature CommunicationsVol. 16(1)
University of British Columbia (CA), National Taiwan University (TW), Kyoto University (JP), Max Planck Institute for Solid State Research (DE), National Center for Theoretical Sciences (TW), RIKEN Center for Emergent Matter Science (JP), National Center for Theoretical Sciences, Physics Division, Tokyo Metropolitan University (JP), The University of Tokyo (JP)
Deutsche Forschungsgemeinschaft, Hattori Hokokai Foundation, Inamori Foundation, Casio Science Promotion Foundation, Murata Science Foundation, Japan Society for the Promotion of Science, Core Research for Evolutional Science and Technology
Sustainable cities and communities, Climate action
Openalex Percentile: Top 1%
Topological Materials and Phenomena
14.96
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