부산대학교 도서관

We studied the theoretical Curie temperature of a dual-phase nanomagnetic system by Monte Carlo simulation of a modified Heisenberg model on a 3D complex lattice consisting of single- and cluster-spins. We also systematically investigated the experimental Curie temperature of a dual-phase nanomagnetic alloy and performed a direct comparison between theory and experiment. The exchange coupling between two component magnetic phases substantially affects the Curie temperature $T_c^A$ of the intergranular amorphous region of a dual-phase nanomagnetic system. The $T_c^A$ depends upon the nanocrystallite size d, the volume fraction Vc and the interspace among crystallites ξ. Large crystallized volume fraction Vc, small grain size d, and thin interphase thickness ξ lead to an obvious enhancement of Curie temperature (ECT) of intergranular amorphous region, whereas the Curie temperature of nanocrystallites $T_c^{\rm cr}$ decreases slightly. By simulation, we worked out a relationship between the reduced ECT and ξ, as $T_c^A/T_c\sim 1/\xi$, and it conforms to the experimental result. In addition, we also simulated the demagnetization of a hard–soft nanocomposite system. The exchange coupling between two component phases affects the cooperativity of two-phase magnetizations, the coherent reversal of magnetizations, and coercivity. [ABSTRACT FROM AUTHOR]