Spin-polarised currents and magnetic domain walls

Abstract

Electrical currents flowing in ferromagnetic materials are spinpolarised as a result of the spin-dependent band structure. When the spatial direction of the polarisation changes, in a domain structure, the electrons must somehow accommodate the necessary change in direction of their spin angular momentum as they pass through the wall. Reflection, scattering, and a transfer of angular momentum to the lattice are all possible outcomes, depending on the circumstances. This gives rise to a variety of different physical effects, most importantly a contribution to the electrical resistance caused by the wall, and a motion of the wall driven by the spin-polarised current.Historical and recent research on these topics is reviewed. * Phone: +44(0)113 3433780

Positive antiphase boundary domain wall magnetoresistance in Fe3O4(110) heteroepitaxial films

“…The length scale over which the magnetization direction changes is determined by material parameters such as the exchange and magnetic anisotropy energies. 1,2 The electrical resistance due to magnetic domain walls in metallic ferromagnets has received considerable attention for a long time. [1][2][3][4][5] Research activity in this area has increased substantially in the recent past due to the advances in material preparation and various nanofabrication techniques which allow one to control the DW dimensions and their number.…”

Dependence of Domain-Wall Depinning Threshold Current on Pinning Profile

“…The topic of current-induced domain-wall (DW) movement [1] has seen growing interest in recent years not only due to its promising applications to spintronics devices, such as magnetic logic gates and magnetic random access memory, but also due to the fascinating underlying physics. Experimental work on this subject includes studies on ferromagnetic thin films [2,3], nanowires [4][5][6][7][8], and wires with patterned pinning sites [9][10][11][12][13].…”

Controlling domain wall pinning in planar nanowires by selecting domain wall type and its application in a memory concept

“…There has been an intensive research interest in the behavior of individual domain walls in nanowires both in terms of the fundamental physics 1 and for potential applications in sensors, 2 logic, 3,4 and memory. For memory applications, domain walls can be pinned at structural features such as notches creating multiple domains and hence multiple memory states which could be read out either sequentially in shift registers 3,5 or directly if an entire nanowire forms the free layer of a magnetic random access memory ͑MRAM͒ cell.…”