Structural and magnetic properties of MnFe1-xCoxGe compounds

The structural and magnetic properties of MnFe1-xCoxGe compounds with x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.85, 0.9, and 1.0 were investigated by means of X-ray diffraction (XRD) and magnetization measurements. XRD shows that the MnFe1-xCoxGe compounds crystallize in the hexagonal Ni2In-type crystal structure for x <= 0.8 and in the orthorhombic NiTiSi-type structure for x > 0.8. The magnetization measurements show that the MnFe1-xCoxGe compounds exhibit a complex magnetic behavior. The Curie temperature increases with increasing of x. The saturation magnetization of the compounds with Ni2In type structure increase with increasing of x and the saturation of the magnetization in the NiTiSi-type structure also increases with increasing x. We investigated the magnetocaloric effects in these compounds by means of magnetization measurements. The maximum magnetic-entropy change observed in these compounds reaches 9 J/kgK for x = 0.8 in a field change from 0 to 5 T at around 289 K.