Magnetization steps at the ferromagnetic transition of (Mn,Fe)2(P,Si) single crystals

Single crystals are highly desirable to study intrinsic properties of phase transitions, unfortunately due to an embrittlement at the transformation, (Mn,Fe)2(P,Si) studies were so far limited to polycrystalline samples. Here, we report the growth of (Mn,Fe)2(P,Si) single crystals which can be cycled across their first-order ferromagnetic transition. In single crystals with optimized composition, detailed magnetization measurements reveal a ferromagnetic transition whose shape is significantly different from polycrystalline samples, with unusual discontinuous magnetization steps induced by temperature or magnetic field leading to a stair-like transition. In contrast to the “virgin effect” of (Mn,Fe)2(P,Si) samples, this behavior is reproducible. This unique magnetic response of some (Mn,Fe)2(P,Si) crystals can be correlated to a microstructure very different from that of the bulk and preserving the clamping/release role played by strains and stresses at the ferro-paramagnetic transformation. On top of offering more details on how the first-order magnetic transition develops in time, space and as a function of the driving parameter, which is of importance for designing functional magnetocaloric materials, the growth of cyclable crystals opens new possibilities for future experiments. [Display omitted] •growth of (Mn,Fe)2(P,Si) crystals cyclable across the ferromagnetic transition.•significantly enlarged thermal hysteresis in crystals compared to the bulk.•successive and reproducible magnetization steps at the ferromagnetic transition.•strains/stresses are responsible for an irregular development of the transition.