Magnetism of High Entropy Silicide RAlSi

High entropy materials are known to experience competition between different characteristics of their parent materials, resulting in compromise which sometimes produces new properties not present in any of the parents. In the case of magnetism, low entropy alloying or doping is expected to disrupt long range order in magnetic materials, producing a broadened magnetic transition or a spin glass phase [1]. However, previous study [2] on a magnetic high entropy oxide found that sharp magnetic transitions may persist despite the random arrangement of multiple magnetic elements. Here, we report a new family of high entropy magnets, RAlSi (HE=Ca, Sr, and lanthanides). Single crystals of RAlSi, composed of five mixed cations at the R site and exhibiting various magnetic orderings in their parent phases, were successfully grown using the flux method. Depending on the choice of elements mixed on the R site, the high entropy crystal can demonstrate ferromagnetic or antiferromagnetic ordering and maintains a sharp transition indicative of long range order comparable to the parent materials in both cases. In addition to exploring the commonality of such entropy protected sharp magnetic transitions, high entropy magnets could allow electronic properties of a material to be tuned through composition without disrupting magnetic ordering, potentially allowing for realization of magnetic topological materials or altermagnets.