The effect of Co vacancy on crystal structure and magnetism of the ternary ferromagnet MnCoGe

Abstract X-ray diffraction, magnetization, and thermo-analysis were conducted on the ternary compounds Mn 1.1 Co 1- x Ge (0≤x≤0.25). Based on the results, the phase diagram in the temperature-concentration plane was determined for this compound system. In the vacancy concentration range 0≤ x ≤0.08, the samples undergo a martensitic transition from the orthorhombic TiNiSi-type structure to the hexagonal Ni 2 In-type structure with increasing temperature. In contrast, samples with x >0.08 crystallize in the Ni2In-type structure across the entire temperature range. In this phase diagram, the magnetostructural transition was not observed, indicating that the magnetostructural coupling of this compound system is weak.