Magnetostructural transition in Gd5Sb0.5Ge3.5
نویسندگان
چکیده
Magnetic and crystallographic properties of Gd5Sb0.5Ge3.5 were investigated using dc magnetization, ac magnetic susceptibility, and heat capacity of an oriented single crystal, combined with temperature and magnetic field dependent x-ray powder diffraction. The compound undergoes an unusual magnetostructural transition at 40 K and a nonmagnetic second-order transition around 63 K. The detailed crystallographic study of Gd5Sb0.5Ge3.5 shows that contrary to the R5(SixGe1−x)4 systems (R is a rare-earth metal), the structural transition occurs without shear displacements of the ∞2[R5T4] slabs (T=Si, Ge, and Sb), and a substantial volume change (−0.5%) does not lead to a change in crystallographic symmetry. The firstprinciples electronic structure calculations show higher interslab than intraslab ferromagnetic exchange interaction indicating that Sm5Ge4 type of structure supports a ferromagnetic ground state in Gd5Sb0.5Ge3.5.
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