Micromagnetic theory of non-uniform magnetization processes in magnetic recording particles

Nucleation of Magnetization Reversal in Individual Nanosized Nickel Wires

“…It is now possible to make a clear link between experiments performed on nanometer-sized single objects (particles, wires, etc.) and the numerical calculations based on the Brown micromagnetic equations [6].…”

“…Extensions of analytical [11] to numerical [6,15] calculations of the micromagnetic equations allow a description of the magnetization reversal process beyond small angle deviations of the magnetization. In cylinders of finite length, the curling mode is immediately followed by the formation of a vortex at one end of the cylinder which sweeps across the sample [16].…”

Magnetic Anisotropy of a Single Cobalt Nanocluster

“…Indeed they are clearly different in intensity and orientation because of the random distribution of the easy magnetization directions. For cobalt, the exchange length is 7 nm which is larger than the 3 nm particle size [18]. In this case, we can use to a good approximation the Stoner and Wohlfarth model [19,20] describing the magnetization reversal by uniform rotation.…”

Magnetic properties of polycrystalline cobalt nanoparticles

“…The single-domain diameter of the particle can be approximately determined by variational or analytical estimates, [7][8][9][10][11][12] or with the help of numerical simulation. [13][14][15][16][17][18][19] It was previously shown 18 that for homogeneous magnetic nanoparticles of a non ellipsoidal shape, such as a cube, a parallelepiped, or a cylinder, it is possible to introduce an effective single-domain diameter, D ef , such that for these particles with a characteristic size D < D ef the lowest energy configuration is a quasiuniform flower state. [19][20][21] In particular, it was shown 18 that the effective single-domain diameters for a cylinder with aspect ratio L x /L z = 1 and for a cube are approximately only 3% and 9% lower, respectively, than the single-domain diameter of an ideal sphere with the same magnetic parameters.…”