High-Magnetic Field X-ray Diffraction Studies on Gd₅(Ge_2−xFe_x)Si₂ (x=0.05 and 0.2)

Abstract

We performed the powder X-ray diffraction measurements in magnetic fields up to 5 T for Gd₅(Ge_1.95Fe_0.05)Si₂ and Gd₅(Ge_1.8Fe_0.2)Si₂. With heating from 8 K, the matrix of Gd₅(Ge_1.95Fe_0.05)Si₂ clearly shows a structural transition from an orthorhombic to a monoclinic structure at the Curie temperature (T_C=276 K). On the other hand, the matrix of Gd₅(Ge_1.8Fe_0.2)Si₂ with the orthorhombic structure in the ferromagnetic state shows two-phases co-existence of the orthorhombic and the monoclinic structures above T_C=303 K, indicating that a small amount of the matrix participates in the transformation. For both samples, the monoclinic structure is suppressed but the orthorhombic structure is enhanced just above T_C by applying a magnetic field, which closely relates to the magnetization process.