Nuclear Electric Quadrupole Interaction of Ir Nuclei in Ferromagnetic Dilute Alloys of Iron and Nickel

NMR of Ir in cubic Fe Ir and Ni Ir alloys shows nuclear quadrupole splitting. By the use of single crystals, it was shown that the principal value of the quadrupole interaction along the direction of the magnetization is almost independent of the orientation of the magnetization with respect to the crystallographic axes. This quadrupole interaction is explained by electric field gradient induced by the electronic spin through spin-orbit coupling, with the assumption that the spin-orbit coupling and splitting of d ε and d γ bands by cubic crystalline field at the impurity site are smaller than the width of the bands. For other impurity neclei in iron or nickel, splitting of NMR lines by quadrupole interaction was not clearly observed and the reason why it was so is discussed.