Specific heat and the influence of hydrostatic pressure on the phase transitions in Ni_(50)Mn_(35)In_(14.25)B_(0.75)

摘要

The magnetic properties, magnetocaloric effects, and martensitic transition in Ni50Mn35In14.25B0.75 have been investigated using specific heat and magnetic measurements as a function of hydrostatic pressure. A shift in the martensitic transition temperature (T-M) toward room temperature (by 35 K to higher temperature) was observed with the application of pressure (P= 0.54 GPa). The isothermal entropy changes obtained from magnetization and heat capacity measurements were found to be in good agreement. A large inverse adiabatic temperature change (Delta T-ad) of 2.7 K was determined from heat capacity data at T-M for a magnetic field change of 1.8 T. The density of states and the Debye temperature were found to be 4.9 states/eV/f.u. and 322 K, respectively. The magnetic entropy analysis agrees fairly well with the theoretical maximal magnetic entropy, R ln(2J+ 1).