Magnetoentropic signatures of phase transitions in room temperature skyrmion hosts*

FeGe and Co_xZn_yMn_z have been demonstrated to host skyrmions at temperatures near and above room temperature, opening up the possibility of a number of practical applications. However, the details of the bulk magnetic phase diagrams have been a subject of much debate. In large part, this is due to the experimental difficulties associated with studying subtle materials properties at high temperature, particularly when large single crystals are not available. Here, we adapt tools developed for studying magnetocalorics to gain new insight about the magnetism of these skyrmion hosts using DC magnetization data. The techniques we have developed are easily applied to almost any material at any temperature between 2 K and 1000 K+, and allow for the rapid determination of a magnetic phase diagram (< 24 hrs.) while also giving quantitative latent heats of field-driven phase transformations. We clearly identify the first-order topological phase transitions as well as the Brazovskii transition and tricritical point in FeGe and demonstrate the entropic implications of each of these transitions.