Dynamic transformations of the internal structure of a moving domain wall in magnetic nanostripes

Abstract

The magnetic field ͑or electric current͒ driven domain-wall motion in magnetic nanostripes is of considerable interest because it is essential to the performance of information-storage and logic devices. One of the current key problems is to understand the complex behaviors of oscillatory domain-wall motions under applied magnetic fields stronger than the so-called Walker field, beyond which the velocity of domain walls markedly drops. In a certain range just above the Walker field, the motions are not chaotic but rather periodic with different periodicities of dynamic transformations of a moving domain wall between the different types of its internal structure. In addition, three different periodicities of the dynamic transformations are calculated, which consist of different types of domain-wall structures that are transformed from one type to another. The transformation periods vary with the field strength and the nanostripe width. This phenomenon can be described by the dynamic motion of a limited number of magnetic topological solitons such as the vortex and antivortex confined in nanostripes. These results provide a considerably better understanding and details of the domainwall motions in soft magnetic nanostripes.

Edge-Soliton-Mediated Vortex-Core Reversal Dynamics

“…Such dynamics have attracted growing interest for their potential applications to future data storage [6][7][8] and processing devices [9,10]. For example, domain wall motion can be described in terms of the dynamics of various types of magnetic topological solitons, i.e., transverse, vortex, and antivortex walls, via the sequential processes of the creation, propagation, and annihilation of them [3,4] in the Walker breakdown regime in magnetic nanostrips or simple motions of single solitons without any transformation of their internal structures [5]. Also, a single magnetic vortex in nanodots can be transformed into a new vortex with its core orientation opposite to the original core orientation via the serial processes of the creation and subsequent annihilation of vortexantivortex (VAV) pairs, with the help of vortex-core (VC) gyration motions [11][12][13][14][15][16][17].…”

“…This work provides a deeper physical insight into the dynamic transformations of magnetic topological solitons in nanoelements. DOI: 10.1103/PhysRevLett.106.147201 PACS numbers: 75.78.Jp, 75.78.Cd, 75.78.Fg Nontrivial inhomogeneous magnetization configurations in the restricted geometries of micrometer-size (or smaller) magnetic elements play crucial roles in the magnetization dynamics occurring on scales of a few tens of picoseconds [1][2][3][4][5]. Such dynamics have attracted growing interest for their potential applications to future data storage [6][7][8] and processing devices [9,10].…”

Magnetic domain-wall dynamics in wide permalloy strips

“…35 Recently we have shown that in the case of even wider permalloy strips than those with VW as the equilibrium DW structure, two additional equilibrium DW structures appear, namely the double vortex (DVW) and triple vortex walls (TVW) 26 . Studies of field and current driven dynamics of DWs in permalloy strips have focused mostly on narrow strips with either TW or VW as the equilibrium DW structure [8][9][10][11][12][13][36][37][38][39][40][41] . In both cases, the DW dynamics exhibits a Walker breakdown 42 , an instability occurring when the DW internal degrees of freedom are excited by a strong enough external driving force.…”

“…In narrow and thin strips with TW as the equilibrium structure, repeated transitions between TWs of different polarities (or signs of the TW internal magnetization) take place via nucleation and propagation of an antivortex across the strip width; we will refer to the transient state as the antivortex wall, or AVW 10 . For wider strips with a VW equilibrium DW, periodic transitions between VW and TW structures are typically observed 10,36 . However, so far little is known about the DW dynamics in even wider strips, especially ones with DVW or TVW as the equilibrium DW structure.…”

Simulation of three-dimensional micromagnetic structures in magnetically uniaxial films with in-plane anisotropy: Static structures

“…At present, a significant surge of interest has been observed in micromagnetics investigations of magnetic structures and their dynamic behavior in nanosized samples (disks [6], stripes [7], wires [8], and tubes [9]), which is related to the development of spintronics devices [10] and new type memory devices [11].…”