Magnetism, magnetotransport properties and their correlation with magnetic field in the semiconductor-type EuMnSb2

Abstract

The semiconductor-type EuMnSb2 single crystal with an orthorhombic structure (space group Pnma, No.62) was synthesized using the Sn-flux method, and its physical properties were systematically investigated by magnetization, specific heat, and resistivity measurements. The magnetic and specific heat features reveal two successive antiferromagnetic (AFM) transitions exist separately at TN1 ∼ 21 K and TN2 ∼ 9 K, which have different responses to external magnetic field, and magnetic anisotropy is enhanced as the temperature is below TN1. When the magnetic field is about 1.7 T and parallels the a-axis of the EuMnSb2 crystal, a spin-flop transition of the AFM order appears. Electronic transport measurements show that the single crystal of EuMnSb2 manifests semiconductor characteristic and magnetic field-induced semiconductor-to-metal transitions. In addition, we observe a colossal negative magnetoresistance for both in-plane and out-of-plane resistivity and two-fold period anisotropic magnetoresistance. Combining magnetic susceptibility, specific heat capacity and resistivity properties, we present a phase diagram which can be divided into AFM semiconductor, paramagnetic semiconductor and paramagnetic metal. These unique properties indicate that EuMnSb2 can provide a platform for investigating the interplay between magnetic order, and charge transport.