The motion of 180° domain walls in uniform dc magnetic fields

Abstract

The equations of motion of a 180° domain wall in an infinite uniaxially anisotropic medium which is exposed to an instantaneously applied uniform dc magnetic field H0 have been integrated numerically. Below the critical field Hc =2παM0 (α is the Gilbert loss parameter and M0 the saturation magnetization), where a steady-state solution is known to exist, it is shown that the wall motion tends smoothly to this solution. Above Hc, the magnetization precesses about the field and a periodic component appears in the forward motion of the wall. Analytic solutions for the wall motion have been found based upon approximations suggested by the computed behavior; these reproduce the computer results very accurately.

High-efficiency resonant amplification of weak magnetic fields for single spin magnetometry at room temperature

“…For all the estimates provided herein, we assume room temperature and that the FM material is YIG, so that α ∼ 10 −5 , µ 0 M F = 0.185 T, and K/M F = 60 mT. 36 For simplicity but without loss of generality, we assume that the FM has the shape of a cube for the estimates given below. For a cube and in the macrospin approximation there is no contribution from shape anisotropy.…”

Enhancing domain wall speed in nanowires with transverse magnetic fields

“…The only variable parameters in the expression are the domain wall length ⌬ ͑extent along the wires length͒ and H drive , the longitudinal driving field but the velocity only increases with the driving field up to the critical Walker field. 3 In this work we attempt to increase the maximum domain wall speed by applying a magnetic field component transverse to the driving field. The application of the transverse field varies the energy landscape of the domain wall which leads to a change in the domain wall length.…”

“…1,2 When a domain wall is driven by a magnetic field parallel to the long axis of the wire, the maximum wall speed is found to be function of, and capped by, the dimensions of the wire. [3][4][5] In addition, the range of applied driving fields for which the wall motion is pure, fast translation is also limited by the wire geometry. The critical field at which wall velocity is the greatest is called the Walker field, above this field the wall progresses slowly along the wire in a series of periodic steps.…”

High domain wall velocities in in-plane magnetized (Ga,Mn)(As,P) layers

“…Working on unpatterned layers and tuning the magnetic anisotropies in GaMnAs(P) alloys would however provide unprecedented understanding and control of the field dependence of the velocity. Moreover these layers should be well suited to achieve high DW velocities because of large DW width 12 , as expected from the well-known onedimensional (1D) model 13,14 for DW propagation.…”