The negative effect of cold working on the magnetocaloric effect across the Curie transition of Mn-based Heusler alloys is highlighted. The results of manual crushing and subsequent heat treatment on the magnetic and magnetocaloric properties of a Ni₅₀Mn₃₄In₁₆ sample are reported. Plausible explanations of the degradation of the magnetocaloric effect by cold working are discussed, on the basis of magnetic and structural measurements performed on a reference sample. The study of the connection between microstructure and magnetic properties of these materials represents a key point for the improvement of Heusler-based magnetic refrigeration.

We present direct measurements of the magnetocaloric effect on a Fe₂P-based compound induced by a milliseconds pulsed magnetic field of 1 T to test their possible use in high frequency (up to 100 Hz) thermomagnetic cycles. The reported measurements were performed with an innovative and versatile non-contact set up based on the mirage effect. The adiabatic temperature change of a MnFeP_0.45As_0.55 sample is presented and compared with measurements performed varying the same magnetic field in a time interval of 1 s and 100 ms. These results demonstrate the absence of kinetic constraints in the first-order phase transition of this sample induced on the milliseconds time scale. The study of the materials' response to millisecond magnetic field pulses represents a fundamental test for the development of more powerful and efficient magnetic refrigerators.