Nuclear Magnetic Resonance in Heusler Alloys: Ni₂MnSn, Co₂MnSn and Ni₂MnSb

Abstract

The internal magnetic fields of Mn and Sn nuclei in Ni₂MnSn, Co₂MnSn and Ni₂MnSb were measured with the spin-echo N. M. R. method, as well as their thermo-magnetic curves. The Curie temperatures measured of Ni₂MnSn and Ni₂MnSb were different from Castellitz’s data, and a sluggish change of the magnetization in Ni₂MnSb was observed, near the Curie temperature. The NMR signals of Mn nuclei were observed in Co₂MnSn, Ni₂MnSn and Ni₂MnSb. The internal magnetic fields were 352.3, 312.7 and 285 kOe, respectively. An unexpected resonance signal appeared in Ni₂MnSb and was interpreted as originating from Mn atoms occupying non-regular sites. The resonance signals of Sn nuclei were also observed in Co₂MnSn and Ni₂MnSn. The internal magnetic fields were 153.8 and 150.4 kOe, respectively. The difference in the internal magnetic fields of the above compounds from those of Cu₂MnSn can be tentatively attributed to the difference in the conduction electron polarization by RKKY interaction.