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  • Open Access

Interaction-enhanced altermagnet in the Hatsugai-Kohmoto model

Ádám Bácsi1,2,* and Balázs Dóra3,2,†

  • *Contact author: bacsi.adam@sze.hu
  • †Contact author: dora.balazs@ttk.bme.hu
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APS Open Sci. 1, 000025 – Published 26 May, 2026

DOI: https://doi.org/10.1103/p54n-mvb8

Abstract

We investigate the interplay between altermagnetic band structures and electronic correlations by focusing on the dx2−y2 altermagnetic generalization of the Hatsugai-Kohmoto model. We find that with increasing interaction, a many-body Lifshitz transition takes place when doubly occupied regions disappear from the Fermi surface and almost all momentum states become fully spin polarized. This is termed interaction-enhanced altermagnet. We find that the dynamical susceptibility, which possesses only transverse nonzero components for small wave vectors, develops a gap proportional to the interaction strength and displays a sharp peak at a frequency increasing with the interaction. Above the Lifshitz transition, this peak moves to the lower gap edge and becomes log divergent. The signal intensity increases with the interaction up until the Lifshitz transition and saturates afterward. The static susceptibility remains unaffected by the correlations and altermagnetism reduces the static transverse response.

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APS Open Sci. 1, 000025– Published 26 May, 2026
Vol. 1
  • Received 17 November 2025
  • Accepted 13 May 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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