To ensure the energy supply of the society of the future, efficient energy generation and energy saving technology must be developed in parallel. To reduce energy loss, the thermoelectric Nernst effect is one possible approach: this thermoelectric effect can convert the flow of heat to beneficial electric voltages, becoming large in certain ferromagnetic materials. However, the large magnetization in ferromagnets has several disadvantages for implementation: For example, a ferromagnet is easily disrupted by an external magnetic field. In antiferromagnets with zero net magnetization, the electric Nernst voltage can be created with the help of an emergent – or fictitious – magnetic field that is a consequence of particle-wave duality in the theory of quantum mechanics. The University of Tokyo and RIKEN researchers targeted the layered material CoNb3S6 which has a chiral crystal structure with a fixed sense of rotation (left- or right-handed). They found that the combination of chiral crystal structure and the antiferromagnetic spin order generates a large emergent magnetic field, which should be understood by the mathematical concept of topology. In this situation, a large ‘topological’ Nernst effect appears in an antiferromagnet despite vanishingly small net magnetization. The researchers’ findings mark a significant step forward in the study of thermoelectric materials and their potential applications in next-generation energy saving and information technologies.
Papers
Journal: Nature Communications
Title: Gapped nodal planes and large topological Nernst effect in the chiral lattice antiferromagnet CoNb3S6
Authors: Nguyen Duy Khanh, Susumu Minami, Moritz M. Hirschmann, Takuya Nomoto, Ming-Chun Jiang, Rinsuke Yamada, Niclas Heinsdorf, Daiki Yamaguchi, Yudai Hayashi, Yoshihiro Okamura, Hikaru Watanabe, Guang-Yu Guo, Youtarou Takahashi, Shinichiro Seki, Yasujiro Taguchi, Ryotaro Arita, Max Hirschberger
DOI: 10.1038/s41467-025-57320-9