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We theoretically study the piezomagnetic effect on the altermagnetic state in κ-type molecular conductors, focusing on its nonrelativistic mechanism. By introducing shear stress as a monoclinic distortion, we evaluate variations in the ef- fective tight-binding model using first-principles calculations. Using the derived parameters, we investigate the Hubbard model and its effective Heisenberg model on the two-dimensional (distorted) κ-type lattice within mean-field approxima- tion. We show that the system exhibits the piezomagnetic effect, i.e., a net magnetization induced at finite temperatures in the undoped insulating state and both in the ground state and at finite temperatures upon doping. In a real-space pic- ture, this uniform magnetization arises from the ferrimagnetic spin structure due to inequivalent spin sites induced by lattice distortion. Meanwhile, in a momentum-space picture, it stems from the s-wave spin splitting of the electron and magnon bands, independent of spin-orbit coupling. We find that this nonrelativistic piezomagnetism remains finite, but becomes smaller in the limit of strong dimerization where the energy gap between the bonding and antibonding orbitals is infinitely large and the d-wave altermagnetic spin splitting is absent, highlighting the importance of the multi-orbital nature.

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• http://arxiv.org/licenses/nonexclusive-distrib/1.0/
  

Keyword: Organic Altermagnet, Non-relativistic Piezomagnetic Effect

Date published: 2025-08-15

Publisher: Physical Society of Japan

Journal:

• Journal of the Physical Society of Japan (ISSN: 13474073) vol. 94 083702

Funding:

• Japan Society for the Promotion of Science 19K03723
• Japan Society for the Promotion of Science 19K21860
• Japan Society for the Promotion of Science 20H04463
• Japan Society for the Promotion of Science 23H01129
• Japan Society for the Promotion of Science 25H00838
• Japan Society for the Promotion of Science 25H01247
• Japan Society for the Promotion of Science 23K25826
• Japan Society for the Promotion of Science 23K03333

Manuscript type: Author's version (Accepted manuscript)

MDR DOI:

First published URL: https://doi.org/10.7566/jpsj.94.083702

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Updated at: 2025-11-11 08:30:06 +0900

Published on MDR: 2025-11-11 08:22:14 +0900