Rare coexistence of disorder-induced Griffiths phase and reentrant spin-glass state in a Heusler alloy Rh2FeAl with high Curie temperature

In this work, we report the synthesis of a Heusler alloy Rh2FeAl with valence electron count (VEC) 29 forming in B2-type structural disorder, where Fe atoms are distributed randomly with Al atoms between 4a and 4b Wyckoff positions (space group Fm3¯m, No: 225). Despite the structural disorder among the moment carrying Fe atoms, the compound exhibits ferromagnetic Curie temperature around TC ∼ 497 K. Nevertheless, the observation of Griffiths-phase (GP) like behaviour at TG ∼ 592 K suggests that atomic disorders brought down the bulk TC by about 95 K. The structural disorder also affects the ordered spin arrangements below TC through the development of a reentrant spin glass (RSG) state at low temperature. Both the GP like behaviour as well as RSG states are rarely observed in Heusler alloys while their coexistence is even rarer. The isothermal magnetisation as well as temperature dependence of resistivity behaviour ruled out the possibility of having half-metallic ferromagnetic characteristic in this material. •Successful synthesis of a 4d based full Heusler alloy Rh2FeAl in disordered B2-type crystal structure.•Despite such crystallographic disorder Rh2FeAl undergoes a ferromagnetic transition at TC ∼ 497 K.•Isothermal magnetization along with magnetic susceptibility confirms a reentrant spin-glass transition at low temperature.•A Griffiths-like phase is also manifested at TG ∼ 592 K indicating local microscopic arrangements of Fe spins.•Such rare coexistence of Griffiths-like phase and reentrant spin glass state is not observed earlier.