Large positive and negative magnetoresistance in the magnetic EuCu4As2 crystal

In this article, we studied the magnetic and transport properties by magnetization, resistivity, and specific heat measurements for EuCu4As2 crystals with a rhombohedral structure. Strongly anisotropic magnetism and rich magnetic phases were observed under magnetic field in this compound. Interestingly, we observed two types of magnetoresistance: a large negative magnetoresistance (−55%, at 35 K, 9 T) near the magnetic transition temperature, due to reduction of magnetic scattering under magnetic field; a large positive magnetoresistance (60% at 2 K, 9 T) at lower temperatures when Eu2+ moments ordering ferromagnetically, similar to that observed in the non-magnetic isostructural analogue SrAg4As2 with possible nontrivial topological bands, which may be related to its special band structure.