Ferromagnetic resonance in an antiferromagnetic crystal EuSn₂As₂

2025/12/15 by Gimazov, I. I., Zhelezniakova, D. E., Zaripov, R. B. +7
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)

paper · doi:10.48550/arxiv.2512.13571

Abstract

We report results of electron spin resonance (ESR) measurements in single crystals of EuSn₂As₂. In the temperature range of antiferromagnetic (AFM) ordering of Eu atoms, T ≤ T_N≈ 24 K, the ESR signal splits into two resonance lines, one of which, at high-field (or low-frequency), is the conventional acoustic AFM resonance mode that occurs at temperatures below T_N. The lower-field (high-frequency) line, as we have proven here, is the ferromagnetic resonance associated with the presence in the layered AFM crystal of a small amount (∼ 3%) of planar nanodefects with a non-zero ferromagnetic (FM) moment. The existence of ferromagnetic nano-inclusions in the bulk of the antiferromagnetic compound makes EuSn₂As₂ a peculiar example of a natural magnetic metamaterial. We believe that the planar FM nanodefects are also inherent in other layered AFM compounds, which explains often observed increase in their magnetic susceptibility upon cooling at T< T_N→ 0.

Citations

• Universal negative magnetoresistance in antiferromagnetic metals caused by symmetry breaking of electron wave functions
• Emergence of Ferromagnetism from Planar Defects in EuSn2As2 Antiferromagnet
• Intrinsic Negative Magnetoresistance in Layered AFM Semimetals: the Case of EuSn₂As₂

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