Anisotropy of the magnetic and transport properties in EuZn$_2$As$_2$

Abstract

Several recent studies have shown that the anisotropy in the magnetic structure of EuCd2As2 plays a significant role in stabilizing the Weyl nodes. To investigate the relationship between magnetic anisotropy and Weyl physics, we present a comparative study between EuZn2As2 and EuCd2As2 that are isostructural but with different magnetic anisotropy. We performed structural analysis, electronic transport, and magnetization experiments on millimeter-sized single crystals of EuZn2As2, and compared the results to those of EuCd2As2. By combining the first principle calculations and neutron diffraction experiment, we identify the magnetic ground state of EuZn2As2 as A-type antiferromagnetic order with a transition temperature (TN = 19.6 K) twice that of EuCd2As2. Like EuCd2As2, the negative magnetoresistance of EuZn2As2 is observed after suppressing the resistivity peak at TN with increasing fields. However, the anisotropy in both transport and magnetization are much reduced in EuZn2As2. The difference could be ascribed to the weaker spin-orbit coupling, more localized d-orbitals, and a larger contribution from the Eu s-orbitals in the zinc compound, as suggested by the electronic band calculations. The same band structure effect could be also responsible for the observation of a smaller non-linear anomalous Hall effect in EuZn2As2 compared to EuCd2As2.