Single-wall dynamics and power law in bistable magnetic microwires

Abstract

The dynamics of a single domain wall in finite glass-coated microwires is reported in the low-field regime below the switching field. The power law of the single domain wall propagating over a large distance is confirmed. Three regions are determined for the propagating domain wall. Below some critical field, H 0 , the domain wall is pinned at the wire's end. Just above that critical field, the wall moves in the adiabatic regime, interacting with the defects during its propagation, with an average velocity of v = S (H − H 0 ) β . At high field, the domain wall propagates in the viscous regime and its average velocity is proportional to the applied magnetic field, H . An analysis of the temperature dependence of the scaling factor β is further reported. It is also shown that the domain wall mobility parameter S is field-independent and is proportional to the domain wall mobility S in the viscous regime.

Single Domain Wall Propagation at Low Fields

“…It has been shown, that at low elds that domain wall dynamics deviates from the linear dependence of the velocity on applied eld given by Eq. 1 [4,8,9]. Instead the (30) domain wall dynamics at low elds is described by power law (Eq.…”

“…2) [6,7]. It is known that power exponent q determines the domain wall shape [4]. At high temperatures, the magnetoelastic contribution is dominant and the domain wall pinning is small.…”

“…Sixtus-Tonks like experiment was used for domain wall dynamics measurements. More details can be found elsewhere [3,4].…”

“…It was also shown, from measurements of temperature dependence of q, that the value of power exponent is determined by the domain wall shape. The mobility parameter S is proportional to the mobility S from equation (1) and hence it is eld independent [3,4].…”

Vortex magnetic structure in circularly magnetized microwires as deduced from magneto-optical Kerr measurements

“…This process results in squared hysteresis loops. 11,12 In the case of vanishing magnetostriction (i.e., Co rich CoFe alloys), the ultrasoft wire exhibits a multidomain structure. In this case, the existing walls can almost freely move in a quasi-reversible way, giving rise to a very high initial susceptibility and to the giant magnetoimpedance effect.…”