Adiabatic measurement of the giant magnetocaloric effect in MnAs
We have studied the compound MnAs with a giant magnetocaloric effect, which has a magneto-structural transition at 316 K. The magnetic phase diagram has been deduced from adiabatic heat-capacity measurements and from cooling and heating curves. The ferroto paramagnetic transition changes with field from 316 K at 0 T to 335.3 K at 6 T. There is a strong thermal hysteresis between 10 and 5 K, depending on field. Direct measurements of the adiabatic temperature change caused by the application of magnetic field were made and compared with the values deduced from heat-capacity data.Moreover, adiabatic field cycles were performed quasi-statically between 0 and 6 T around the phase coexistence region, showing the strength of the effect in each phase and on the coexistence lines.
Keywordsgiant magnetocaloric effect heat capacity heating and cooling curves magnetic phase diagram
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