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Updated: Sep 13, 2025
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Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
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Quasisymmetry-Constrained Spin Ferromagnetism in Altermagnets
Mercè Roig1,2, Yue Yu2, Rune C Ekman1
1University of Copenhagen, Niels Bohr Institute, DK-2100 Copenhagen, Denmark.
Physical Review Letters
|July 31, 2025
Summary
Altermagnets exhibit an anomalous Hall effect (AHE) linked to their spin-orbit coupling (SOC). This study reveals a new symmetry explaining varying ferromagnetic moments and magnetic anisotropy in these materials.
Area of Science:
- Condensed matter physics
- Materials science
- Spintronics
Background:
- Altermagnets break time-reversal symmetry, enabling an anomalous Hall effect (AHE) dependent on the Néel vector.
- The AHE typically correlates with the ferromagnetic spin moment due to shared symmetry.
- Density functional theory (DFT) reveals varying AHE magnitudes and negligible ferromagnetic moments in different altermagnetic compounds.
Purpose of the Study:
- To explain the observed variations in ferromagnetic spin moments and AHE magnitudes in altermagnets.
- To introduce a unifying theoretical framework for understanding altermagnetism.
- To provide tools for predicting Néel vector orientation and magnetic anisotropy.
Main Methods:
- Analysis of realistic minimal models for altermagnetism.
- Investigation of spin-orbit coupling (SOC) effects.
- Derivation of analytic expressions for magnetic anisotropy energy.
Main Results:
- Discovery of a general SOC-enabled quasisymmetry: the uniaxial spin space group.
- Explanation of the amplitude of the ferromagnetic spin moment across diverse altermagnetic materials.
- Development of analytic formulas for magnetic anisotropy energy.
Conclusions:
- The uniaxial spin space group provides a fundamental explanation for ferromagnetic spin moment variations in altermagnets.
- Analytic expressions for magnetic anisotropy energy simplify the identification of preferred Néel vector orientations.
- This work offers a deeper understanding of altermagnet properties and their potential applications in spintronics.
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