Antiferromagnetic domains in a single crystal of the A-type spin-7/2 trigonal topological insulator EuSn₂As₂

EuSn₂As₂ is a trigonal A-type antiferromagnetic topological insulator with the moments aligned in the $ab$ plane and with a N\'eel temperature TN = 23.5 K. Here we report that an EuSn₂As₂ crystal exhibits a broad peak at Hc1 = 1100 Oe in the field derivative dMab/dH of the $ab$-plane magnetization Mab(H) at temperature $T=2$ K, demonstrating the presence of trigonal antiferromagnetic domains. We model these Mab(H,\,T=2\, K) data and obtain the trigonal anisotropy-energy coefficient K₃ that is 13.3 and 3.7 times larger than those we previously reported for single crystals of the trigonal compounds EuMg₂Sb₂ and EuMg₂Bi₂, respectively.