Alternate cycles of isothermal magnetization and adiabatic demagnetization applied to a magnetocaloric material can drive refrigeration in very much the same manner as cycles of gas compression and expansion. The material property of interest in finding candidate magnetocaloric materials is their gravimetric entropy change upon application of a magnetic field under isothermal conditions (ΔSM ). This is a complex property, and it is difficult to screen materials for such an entropy change without actually carrying out the relevant time- and effort-intensive magnetic measurements. We introduce a simple computational proxy, based on performing non-magnetic and magnetic density functional theory calculations, that appears to correlate very well with experimentally measured magnetic entropy change values across a wide range of ferromagnets. This proxy, which we refer to as the magnetic deformation ΣM , is a measure of how much the unit cell deforms when comparing the relaxed structures with and without the inclusion of spin polarization. The proxy has been tested against 34 known magnetocaloric materials, including ten samples newly measured for this investigation. It has then been used to screen more than 130 ferromagnetic materials for which magnetic entropy changes have not yet been reported, identifying around 30 compounds as being especially promising for further study. MnCoP, with TC = 575 K, is an example of a new magnetocaloric with maximum ΔSM = −6.0 J kg−1 K−1 for ΔH = 5 T. In evaluating this proxy and performing these predictions, we have aggregated and calculated many properties of magnetic materials. We share this data via a new web-based tool that allows for visualization and exploration of material properties in a wide range of magnets.

Using a dataset of magnetic material properties to screen for magnetocalorics

253rd National Meeting (2017)

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