Magnetostructural phase transitions and magnetocaloric effects in MnNiGe_(1-x)Al_x

摘要

The thermomagnetic and magnetocaloric properties of the MnNiGe_(1-x)Al_x system have been investigated by magnetization and differential scanning calorimetry (DSC) measurements. The presence of first-order magnetostructural transitions (MSTs) from hexagonal ferromagnetic to orthorhombic antiferromagnetic phases has been detected for x= 0.085 and 0.09 at 193 K and 186K, respectively. The values of latent heat (L = 6.6 J/g) and corresponding total entropy changes (ΔS_T = 35 J/kg K) have been evaluated for the MST (x = 0.09) from DSC measurements. The magnetic entropy change for x = 0.09 (ΔS_M=17.6 J/kg K for 5T) was found to be comparable with well-known giant magnetocaloric materials, such as Gd_5Si_2Ge_2, MnFeP_(0.45)As_(0.55), and Ni_(50)Mn_(37)Sn_(13).