Nuclear ferromagnetic resonance on Co2B and on some dilute alloys

The NMR of Co⁵⁹ at 4.2 K in the compound Co₂ B and in the series (Co_0.99X_0.01)₂B where X = Ti, V, Cr, Mn, Fe and Ni is developed in this paper. The NMR spectrum of Co₂B shows a single narrow line which indicates that the easy magnetization direction is parallel to the tetragonal axis. In a static external field the shift of the line indicates that the hyperfine field is negative.Spin-lattice relaxation time T₁ measurements show that the density of states at the Fermi level reaches a maximum in the vicinity of X = V, Cr, in agreement with previous magnetic, resistivity and specific heat investigations. These results are interpreted by the virtual bound state concept.