NMR Study in Dilute CrVCo and MoReCo Alloys

抄録

Magnetic state of Co impurity in Cr_1−xV_xCo and Mo_1−xRe_xCo alloys were investigated systematically by NMR.
In CrVCo alloys, the internal field at ⁵⁹Co in magnetically ordered state decreases with the increase of x associated with the decrease of Co moment. ⁵⁹Co resonances due to nonmagnetic Co atoms were observed for x≥0.2. The Knight shift, K, and nuclear spin-lattice relaxation time, T₁, show that Co atoms become gradually magnetic when x decreases below x=0.4. For x=0.2 and 0.25 alloys, the results of NMR and magnetic susceptibility indicate the coexistence of magnetic and nonmagnetic Co atoms.
In MoReCo alloys, K and T₁ show that Co atoms become gradually nonmagnetic with the increase of x.
K and T₁ in both alloy systems were analyzed using the modified Korringa relation which was substantiated by Shiba for the ground state of the Anderson model.