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

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 angstrom, b = 10.5183 angstrom and c = 5.8001 angstrom, consists of two kinds of Al-Ge clusters and the slanted Gd3 isosceles triangles Delta and reversal del 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 Delta up arrow and reversal Gd3 del down arrow. 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.

Automated summary

The transition from tetragonal to orthorhombic structure of GdAlGe occurs at 1204K. The material exhibits antiferromagnetic order with positive magnetoresistance, attributed to disorderedly magnetic scattering during magnetizing process.