Phase transitions and magnetocaloric effect in Mn3Cu0.89N0.96

Abstract

We report a large magnetic entropy change observed in the antiperovskite Mn3Cu0.89N0.96. Based on the heat flow peak measured by differential scanning calorimetry, the total entropy change according to the structural transition (tetragonal to cubic) was calculated to be ∼60Jkg–1K–1 while the magnetic entropy change accounts for ∼22.5% of the total entropy under a 50kOe magnetic field at 145K. To clarify the origin of the magnetic entropy change, we managed to control the structure transition using a magnetic field. It was found that the magnetic entropy change originates from the transformation from antiferromagnetic (AFM) to ferromagnetic (FM) as well as from the phase transition from cubic to tetragonal under the magnetic field. In the tetragonal phase, a magnetic field can drive the AFM component to transform gradually to the FM component. The magnetic field can also change the phase fraction in the tetragonal and cubic two-phase coexistence region, a similar behavior to that induced by temperature. In the current system, only 5.4% of the cubic phase transforms to the tetragonal phase at 5Tesla (T), indicating there is still much latent entropy in Mn3Cu0.89N0.96.