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Dirac points and topological phases in correlated altermagnets

Lorenzo Del Re*

  • *Contact author: l.delre@fkf.mpg.de; lorenzo.re@uni-wuerzburg.de
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Phys. Rev. Research 7, 033234 – Published 10 September, 2025

DOI: https://doi.org/10.1103/7nvm-s225

Abstract

We explore a two-dimensional Hubbard model adapted to host altermagnetic states. Utilizing Hartree-Fock (HF) and dynamical mean-field theory (DMFT), we uncover that the magnetic solutions of this model feature Dirac points in their spectrum. HF predicts a gap opening at a critical interaction strength, a result corroborated by DMFT calculations at zero temperature. However, at finite temperature and high interaction strengths, Dirac points re-emerge at high energies in the spectral function, even if they are absent in the noninteracting and HF-predicted band structures. Analytical arguments reveal that this phenomenon arises near Mott insulating solutions from the frequency dependence of the self-energy, a behavior not captured by static mean-field theory. We identify distinctive dynamical signatures of correlated altermagnetic states in the spin-resolved optical conductivity, notably a double-peak structure likely linked to high-energy Dirac conelike bands. Moreover, the spin-resolved response exhibits spin-selective activation at different photon energies, pointing to potential applications in spin-dependent optical control. We also propose perturbations to the model that can induce a topological gap in the spectrum, leading to a transition from topologically trivial to nontrivial states by varying doping, interaction strength, and temperature.

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Phys. Rev. Research 7, 033234– Published 10 September, 2025
  • Received 4 September 2024
  • Accepted 11 August 2025
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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. Open access publication funded by Max Planck Society.

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