Investigation of magnetocaloric effect in MnCoGe-based compounds

The magnetocaloric effect is a key mechanism for developing eco-friendly cooling technologies, and materials exhibiting a large magnetic entropy change are highly desirable. MnCoGe, with a magnetic transition temperature near room temperature, is a promising magnetocaloric material [1]. We have studied the structural, magnetic, and magnetocaloric properties of vanadium and carbon substituted MnCoGe compounds. The room temperature X-ray diffraction pattern of the Vanadium doped sample exhibits hexagonal structure with a=b= 4.091(1) Å and c=5.300(1) Å. MnCoGe exhibits ferromagnetic behaviour, and Vanadium substitution shifts the magnetic transition temperature to 269 K. It shows an effective magnetic moment of 7.3 μ_B/f.u. and a positive Curie–Weiss temperature of 256 K. A saturation magnetization of nearly 3.4 μ_B/f.u. is observed from the M-H curve measured at 60 K. From the isothermal magnetization curves, the magnetic entropy change (ΔS_M) has been calculated to be ~5.5 Jkg^-1K^-1 under an external magnetic field of 3 T, near the magnetic transition temperature. The effect of carbon doping on the structural and magnetic properties of MnCoGe will also be discussed in this presentation.

[1] S.C. Ma, Y.X. Zheng, H.C. Xuan, L.J. Shen, Q.Q Cao, D.H. Wang, Z.C. Zhong, Y.W. Du, Large roomtemperature magentocaloric effect with negligibble magnetic hystersis losses in Mn_1-xV_xCoGe alloys, J, Magn. Magn. Mater. 324 (2012) 135-139.