We have studied the antiferro-ferromagnetic first-order transition which occurs in the giant magnetocaloric compound Mn3GaC by heat capacity at zero field and at H=5T. At H=0 we have found transitions at Tt1=155.5K and Tt2=165.2K in addition to the ferro-paramagnetic transition at TC=248K. The first one has a large anomalous entropy ΔS/R=0.36 and a strong field dependence. Direct measurements of the temperature change upon adiabatic application of magnetic field gave ΔTS≅-5K, practically independent of the initial temperature and field, over a wide temperature range below Tt1. The results are explained in terms of the magnetic phase diagram.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics