Magnetism in an altermagnetic candidate EuAgAs

EuAgAs crystallizes in the centrosymmetric space group P6₃/mmc and is predicted to host an accidental Dirac cone in its paramagnetic state [1]. It undergoes an antiferromagnetic transition at T_N = 14 K. Density functional theory (DFT) calculations have predicted an A-type antiferromagnetic (AFM) configuration as the most likely magnetic ground state, which results in the emergence of Dirac-type surface states upon this magnetic ordering [1]. Furthermore, a large topological Hall effect (THE) has been reported in this material [2]. The DFT-predicted magnetic structure is also compatible with altermagnetism. Here, we present the magnetotransport properties and the magnetic neutron diffraction results of EuAgAs to clarify the microscopic origin of the observed THE.

[1] Jin, Y., Zeng, X. T., Feng, X., Du, X., Wu, W., Sheng, X. L., ... & Yang, S. A. (2021). Multiple magnetism-controlled topological states in EuAgAs. Physical Review B, 104(16), 165424.

[2] Laha, A., Singha, R., Mardanya, S., Singh, B., Agarwal, A., Mandal, P., & Hossain, Z. (2021). Topological Hall effect in the antiferromagnetic Dirac semimetal EuAgAs. Physical Review B, 103, L241112.