Magnetostructural phase transitions and magnetocaloric effects in MnNiGe1-xAlx

The thermomagnetic and magnetocaloric properties of the MnNiGe1-xAlx 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 193K and 186 K, respectively. The values of latent heat (L = 6.6 J/g) and corresponding total entropy changes (Delta S-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 (Delta SM = 17.6 J/kg K for 5 T) was found to be comparable with well-known giant magnetocaloric materials, such as Gd5Si2Ge2, MnFeP0.45As0.55, and Ni50Mn37Sn13. (C) 2012 American Institute of Physics. [doi:10.1063/1.3681798]