Current-induced displacements and precession of a Bloch wall in Ni-Fe thin films

Abstract

Rectangular or exponential current pulses of duration 20.1 ys traversing a Bloch wall are found to induc.e wall displacements Ax<10 ,um/pulse in a NisiFer, film of thickness ~263 nm. The critical current density for wall displacement is j,, 1.35 X IO6 A/cm', about 20-200 times lower than for NCel or cross-tie walls investigated earlier. Wall motion arises probably from the precession of wall spins under the influence of the "s-d exchange torque" exerted by conduction electrons crossing the wall. The low j, value and easy precession of spins in a Bloch wall reflect the very small value 2 300 FT of the wall demagnetizing field which opposes spin orientation out of the wall plane in films of this thickness. A dc in-plane hard-axis field causes a linear decrease of j,. A dc easy-axis fleld smaller than H, produces only a very slow decrease of j,

Reduction of Threshold Current Density for Current-Driven Domain Wall Motion using Shape Control

“…Current-driven domain wall (DW) motion has attracted much attention from the viewpoint of applications because this effect makes it possible to switch the magnetic configuration without an external magnetic field 1), 2) . The effect has been convincingly confirmed by a series of experiments on magnetic thin films [3][4][5][6][7][8] and magnetic nanowires [9][10][11][12][13][14][15][16][17][18][19][20] . However, the threshold current densities required for the current-driven DW motion (J C ) are still high, 10 11 -10 12 A/m 2 for single ferromagnetic metal layer circuits [9][10][11][12][13][14][15][16] and on the order of 10 10 A/m 2 for spin-valve ferromagnetic nanowires [17][18][19] .…”

Pulsed-current-induced domain wall propagation in Permalloy patterns observed using magnetic force microscope

“…The global field exerts torque on the wall causing an S-shaped distortion of a Bloch wall and makes adjacent walls move in opposite directions. Another form of global field exerts a torque on the domain walls and reduces the coercivity during oscillation of domain wall after the pulse [11]. It can thus induce ballistic wall motion after the end of the pulse with much less current density.…”

Universal charge and current on magnetic domain walls in Weyl semimetals

“…Racetrack memory technology, experimentally realized in 2008, uses magnetic domains in ferromagnetic nanowires for highperformance information storage 2 . It is essential for such applications to control the motion of DWs; besides the application of external magnetic fields, spin-transfer torque coming from a spin-polarized current via the s-d exchange interaction is one of the major approaches to drive DW motion [3][4][5] . An alternative way has recently been proposed by using spin-orbit torques, which are induced in spin-orbit-coupled materials by the RashbaEdelstein effect and the spin Hall effect [6][7][8][9][10][11][12][13][14] .…”