HYPERFINE INTERACTIONS OF B-12 IMPLANTED IN FERROMAGNETIC NICKEL

Temperature dependences of hyperfine interactions of 12B implanted in Ni were investigated in the temperature range of 6 K–730 K by the NMR method with use of polarized 12B produced in a nuclear reaction and the asymmetric β decay. Two kinds of hyperfine fields with different signs were observed (B+hf=+4.161 ±0.022 kG and B-hf= -1.611 ±0.021 kG at 6 K), which indicated that the implanted 12B were trapped in two different sites (S+ and S-. respectively). The spin-lattice relaxation times T1 and the population rates at the two sites were studied. Near the Curie temperature, an effect of critical slowing-down of the spin-spin correlation was observed as steep variation of T1. The behavior of local field around TC was also studied by varying the external field. Results of these experiments near TC indicate itinerant nature of the electron-spin structure in nickel. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.