Griffiths phase arising from local lattice distortion and spin glass above the Curie temperature in Ni2MnSb polycrystalline Heusler alloy

In this work, the phenomenon of downward deviations from the Curie-Weiss law is found above the Curie temperature (329--458 K) in Ni₂MnSb polycrystalline Heusler alloy, and it was confirmed by the change in inverse magnetic susceptibility under different magnetic fields that it is the Griffiths phase. This abnormal phenomenon can be attributed to short-range nanoferromagnetic clusters caused by local lattice distortion within the paramagnetic state. The ac magnetic susceptibility further showed characteristics of long-range disordered and short-range ordered glassy magnetic states in Griffiths phase range, where the magnetization intensity of the spin glass state has a frequency dependence. This work revealed the nature of the Griffiths phase in Heusler alloys and observed the characteristics of spin glass at high temperatures, providing experimental evidence and support for the study of high-temperature spintronics.