Spin-dependent electron momentum density in the Ni2MnSn Heusler alloy - art. no. 205115

The spin-dependent electron momentum distribution in Ni2MnSn Heusler alloy single crystals was studied using 270 keV circularly polarized synchrotron radiation, through magnetic Compton profile measurements, on the high energ y inelastic scattering beamline at SPring-8. The experiments were carried o ut for the three principal crystallographic directions [100], [110], and [1 11] at 10 K. The results show that the conduction electrons have a negative spin polarization of 0.34 mu (B); the 3d spin moment on the nickel site wa s found to be negligible. A band structure calculation was performed includ ing a hyperfine field study using the full potential linearized augmented p lane wave (FLAPW) method, with the generalized gradient approximation (GGA) for the electronic exchange and correlation. The spin moment on the Mn sit e at 10 K was observed as 4.39 mu (B). The spin-dependent Compton profiles for the [100], [110], and [111] directions reported here show anisotropy in the momentum density, which is in good agreement with the FLAPW-GGA result s, based on a ferromagnetic ground state. The hyperfine fields calculated w ere compared with previously calculated hyperfine field of Cu2MnAl and Co2F eGa Heusler alloys. From the comparison it is seen that the value of H-val (valence contribution to the hyperfine field) is roughly proportional to th e spin polarization (m(s)) of the s electrons at the X (Ni,Cu,Co) and Y (Mn of Ni2MnSn and Cu2MnAl, Fe of Co2FeGa) atom positions.