Spin-Dynamics and Muon Spin Relaxation Study of the Antiferromagnetic Semimetal EuSb₂

EuSb₂ is an antiferromagnet [1] and a topological semimetal [2], which makes it a great platform for studying interactions between topology of conduction bands and ordered spins. We study the antiferromagnetic state (T_N = 26.5 K) using magnetic susceptibility on single crystals [3], and study the spin dynamics using muon spin-relaxation. The temperature dependence of zero-field muon relaxation reveals increased dynamics below 5 K well inside the antiferromagnetic state [3], and we find an increase in high-frequency AC susceptibility measured along the c∗-axis below 5 K. We propose that the dynamics observed originate from competition between the spins aligned in the ab-plane and spontaneous fields that develop along the c∗-direction. Furthermore, transverse-field muon spin relaxation study reveals a splitting in the oscillating frequency above T_N, which originates from the hyperfine-splitting of the Eu²⁺ (S=7/2) state.

[1] F. Hulliger, and R. Schmelczer. J. Solid State Chem., 26, 389 (1978).

[2] M. Ohno, et al. Phys. Rev. B 103, 165144 (2021).

[3] M. Oudah, et al., In preparation (2024).