On the magnetocaloric effect in d-metal pnictides

Recently, the potentialities to develop large magnetocaloric contributions close to room temperature were pointed out in MnFe(As,P). Here, we aim to better underline the main characteristics of the magnetoelastic effect exhibited by many of the d-metal pnictides with formulae MM′X. We have performed systematic neutron diffraction experiments, thus allowing the anticipation of the different contributions to entropy. High magnetic field measurements, in particular under pressure, were performed to quantify the most pertinent (T, P, H) of the phase diagrams. Finally, complete insights of the electronic polarisation instabilities were deduced from KKR-CPA band structure calculations. All fundamental analyses lead to confirm the very interesting magnetocaloric characteristics exhibited by the MM′X series. In parallel, we have currently quantified the change of entropy at the transition to deduce the magnetocaloric contribution. Here, we report a first analysis of the crystal structure and magnetic peculiarities of selected compounds, from a series we studied for a long time.