Magnetic and magnetocaloric properties of Co doped Ni-Mn-Sn Heusler alloys at high magnetic field and pressure*

The magnetic and magnetocaloric properties of Ni₄₅Mn₄₃CoSn₁₁ have been investigated using direct method for magnetic field changes up to 14 T, heat capacity measurements, and magnetization with hydrostatic pressure applications. A large reversible magnetocaloric effect resulted in a ΔT_ad of about =−11 K and 5 K for a magnetic field change of 14 T in the vicinity of magnetostructural (T_A~260 K) and magnetic (T_C~320K) transition, respectively. The impact of thermomagnetic history on ΔT_ad at high magnetic fields has been revealed. Significant changes in the relaxation time of ΔT_ad depending on the type of phase transitions, magnetization, and demagnetization cycle are discussed. The density of states and Debye temperature have been estimated from heat capacity measurements. The mixed effects of pressure and magnetic field on the transition temperature is discussed.