Micromagnetism of two-phase quasi-single-domain spherical particles

Methods of micromagnetism theory werc used for investigation of stability of homogeneously magnetized state of two-phase quasi-single-domain particles with uniaxial magnetic anisotropy. Spherical particles with surface layers differing from the nucleus by the values of constants of magnetic anisotropy, exchange interaction, saturation magnetization are considered. The functional form of occurring heterogeneous distribution of magnetization and critical destruction fields of homogeneously magnetized state were obtained. It is shown that even very thin surface layer affects extremely in some cases on studied characteristics. The correct description of micromagnetic behaviour of real small particles requires consideration of heterogeneity of magnetic parameters in surface layer. Results of applying mentioned theory to particles with SmCo5 as a nucleus and cobalt or Sm2Co17 as surface layers