Magnetic and transport properties of orthorhombic rare-earth aluminum germanide GdAlGe

Abstract The structure, magnetic and transport properties of the orthorhombic rare-earth aluminum germanide GdAlGe are systematically studied using X-ray diffraction, scanning electron microscopy (SEM), magnetic and electric measurements. A phase transition from tetragonal to orthorhombic structure occurs at 1204 K. Orthorhombic GdAlGe, which crystallizes in YAlGe-type structure (Cmcm, N 63, oS12) with lattice parameters a = 4.0605 A, b = 10.5183 A and c = 5.8001 A, consists of two kinds of Al-Ge clusters and the slanted Gd3 isosceles triangles Δ and reversal ∇ with inversion symmetry. GdAlGe orders antiferromagnetically with a Neel temperature of 34 K, it might be due to the exchange coupling interaction of slanted magnetic isosceles triangles Gd3 △↑ and reversal Gd3 ∇↓. Magnetic transport is relative to the magnetic scattering between spins of the conduction electrons and magnetic excitations. The positive magnetoresistance MR with a maximum of 23% is obtained, this phenomenon might be due to disorderedly magnetic scattering during the magnetizing process.