COMPUTER-SIMULATION OF MAGNETIZATION REVERSAL - THE EFFECT OF SHAPE AND UNIAXIAL CRYSTALLINE ANISOTROPY

The Landau-Lifshitz-Gilbert equation has been used to compare the hysteresis loops and magnetization-reversal mechanisms of a cubic particle, with uniaxial crystalline anisotropy, and a 2:1-aspect-ratio elongated particle. The switching fields of these particles were 700 Oe. The cubic particle exhibited a square hysteresis loop, but the elongated particle had a nonsquare hysteresis loop due to the tilting of spins in the surface layers. Magnetization reversal for the elongated particle was initiated at the surface layers. For the cubic particle the reversal was initiated at an edge of the particle and spread through to the central elements. Differences between the hysteresis loops and reversal mechanisms, for the different particles, are attributed to the different nature of the magnetic anisotropies.