Magnetic structure of Gd5Si2Ge2 and Gd5Si2Ge1.9M0.1 (M = Ga, Cu).
Powder x-ray diffraction patterns of the doped compounds Gd5Si2Ge1.9M0.1 (M = Ga, Cu) show the same crystal structure, orthorhombic Gd5Si4-type, in the ferromagnetic and paramagnetic phases. This is different from Gd5Si2Ge2, whose paramagnetic phase is monoclinic. The magnetic structure at low temperature, solved from diffraction experiments with hot neutrons, is the same in all the three compounds, collinear ferromagnetic with moments along the crystal b-axis, or FyFBy according to Bertaut’s notation. These results, combined with those of heat capacity and magnetocaloric effect, indicate, similarly to Gd5Si4, a second-order, purely magnetic, transition in the doped compounds explaining the absence of hysteresis.