Unraveling Low‐Temperature Ruderman–Kittel–Kasuya–Yosida‐Type Cluster Spin Glass‐Like Behavior in Mn ₂ (Ti _0.2 Fe _0.8 )Sn Alloy

Low‐temperature (∼120 K) cluster spin glass (SG) like behavior is observed in high‐quality polycrystalline metastable full Heusler‐like alloy: Mn 2 (Ti 0.2 Fe 0.8 )Sn, which, at room temperature (RT), exhibits an exceptional Mg 3 Cd (or Ni 3 Sn) type hexagonal structure (Space group P6 3 /mmc, no. 194, Strukturbericht designation‐D0 19 ) instead of a cubic structure like full Heusler alloy (FHA). Low‐temperature cluster SG ordering is investigated through temperature‐dependent AC susceptibility at five frequencies, with data fitted using the Vogel–Fulcher law model (VFLM) and critical slowing down model, yielding a Mydosh parameter of 0.0089. Additional evidence from field‐cooled cooling memory effect, temperature‐dependent coercivity, and isothermal temporal relaxation of remanent magnetization fitted via the Kohlrausch Williams Watt model further supports the presence of cluster SG behavior. The nonzero Vogel–Fulcher temperature and absence of universal scaling in M versus H / T curves rule out noninteracting superparamagnetism, reinforcing SG characteristics. Using Tholence criteria, the SG is identified as Ruderman–Kittel–Kasuya–Yosida‐(RKKY) type, likely driven by geometric frustration or quenched disorder, as indicated by the frustration parameter, X‐ray diffraction, and Raman studies. This research, undoubtedly, enlightens our understanding of complex magnetic behavior with SG‐like phase formation in FHA, having an exceptional structure, a unique microstructural morphology, and a Curie temperature in the proximity of RT.