Structural and Magnetic Properties of MnCo_1−xFe_xGe_1−ySi_y (x, y = 0, 0.5)

抄録

Magnetic and structural properties of MnCo_1−xFe_xGe_1−ySi_y (x, y = 0, 0.5) were investigated using X-ray powder diffraction and magnetization measurements in the temperature (T) range from 5 to 370 K and in magnetic fields up to μ₀H = 5 T. At room temperature, MnCoGe and MnCoGe_0.5Si_0.5 were the orthorhombic crystal structure (M-phase), MnCo_0.5Fe_0.5Ge was the hexagonal crystal structure (P-phase), and MnCo_0.5Fe_0.5Ge_0.5Si_0.5 had two-phase coexistence of the M- and P-phases. MnCoGe and MnCo_0.5Fe_0.5Ge were a simple ferromagnetic and their Curie temperatures (T_C) were determined to be 340 K and 200 K, respectively. MnCoGe_0.5Si_0.5 and MnCo_0.5Fe_0.5Ge_0.5Si_0.5 in μ₀H ≤ 1 T showed a gentle dip in thermomagnetic curves at 10 ≤ T ≤ 100 K below T_C which disappears when a magnetic field of μ₀H > 3 T was applied. The magnetization curves of MnCoGe_0.5Si_0.5 and MnCo_0.5Fe_0.5Ge_0.5Si_0.5 at 5 K exhibited that a metamagnetic transition with the magnetic hysteresis in 0 < μ₀H < 3 T. Our results suggest that substituting Fe for Co in MnCoGe system weakens the ferromagnetic interaction, whereas substituting Si for Ge strengthens the antiferromagnetic interaction.

Magnetization curves of MnCo_1−xFe_xGe_1−ySi_y (x, y = 0, 0.5) at 5 K. MnCoGe_0.5Si_0.5 and MnCo_0.5Fe_0.5Ge_0.5Si_0.5 show a metamagnetic transition with a magnetic hysteresis.