Magnetism and Anomalous Hall Effect in the Antiferromagnetic Semimetal Euagsb

Abstract

Magnetic topological materials have attracted significant attention due to their complicated magnetism and abundant topological states. Here, we report an antiferromagnetic (AFM) topological material EuAgSb with a hexagonal structure (space group P63/mmc, No.194), whose high-quality single crystals were synthesized using the flux method. The magnetic susceptibility shows an AFM transition at TN = 6.8 K, which is further supported by specific heat capacity and resistivity measurements. The isothermal magnetization indicates that all Eu spins are completely polarized along the magnetic field direction when the magnetic fields parallel to the c-axis and the ab-plane are higher than 5.0 T and 3.6 T, respectively. The resistivity firstly decreases with the decreasing temperature and increases abnormally near the AFM transition temperature TN, which may be related to the enhancement of spin scattering induced by the spin fluctuations. The magnetoresistance (MR) for both field directions show obvious negative MR at 9 T. The negative MR persists well above TN, and gradually transitions to a positive MR as temperature further increases. The Hall resistivity indicates that holes are dominant carriers in EuAgSb, and the carrier density is almost temperature independent. In addition, the Hall resistivity exhibits a hump-like anomaly below TN, which can be attribute to the anomalous Hall effect and topological Hall effect. In conclusion, our studies suggest that EuAgSb is a candidate magnetic topological semimetal, which provides a platform for further exploring the coupling between magnetic order and the topology of bands.

Keywords: Topological semimetal, Antiferromagnetic transition, Anomalous Hall effect, Topological Hall effect