Voltage-gated pinning in a magnetic domain-wall conduit

Abstract

In spintronic devices relying on magnetic domain-wall (DW) motion, robust control over the DW position is required. We use electric-field control of perpendicular magnetic anisotropy to create a voltage-gated pinning site in a microstructured Pt/Co/AlOx DW conduit. A DW pins at the edge of a gate electrode, and the strength of pinning can be tuned linearly and reversibly with an efficiency of 0.22(1) mT/V. This result is supported by a micromagnetic model, taking full account of the anisotropy step at the gate edge, which is directly caused by a change in the electron density due to the choice of material.

Reversible Electric-Field-Driven Magnetic Domain-Wall Motion

“…The strength and symmetry of the magnetic anisotropy, however, are preserved upon repeated domain-wall cycling in an applied electric field. Thus, contrary to other electric-field effects [13][14][15][16][17][18][19][20][21][22][23][24][25], the mechanism discussed in this paper does not alter the magnitude of magnetic anisotropy. Instead, the magnetic domain wall in the Fe film follows the sideways motion of an anisotropy boundary that is induced by a ferroelectric a-c domain wall in the BaTiO 3 substrate, while the distinctive magnetic anisotropies on top of the a and c domains are conserved.…”

“…This notion has led to various demonstrations of electric-field control over the pinning strength and velocity of magnetic domain walls via voltage-induced changes of magnetic anisotropy. Examples include the use of dielectric gates or ferroelectric films to manipulate the magnetic anisotropy via charge modulation or band shifting [13][14][15][16][17][18][19][20]. Other promising methods utilize strain coupling to piezoelectric materials [21,22] or electricfield-induced ionic diffusion [23].…”

Modification of perpendicular magnetic anisotropy and domain wall velocity in Pt/Co/Pt by voltage-induced strain

“…Even with a decrease of an order of magnitude, the current required to drive the magnetization reversal and the consequent Joule heating would constrain the packing density of component nanostructures in memory devices, as well as waste energy 5 . There is thus much interest in reducing the energy barrier to magnetization reversal, for example by electric field 8 9 10 11 or mechanical strain 12 13 14 15 16 17 18 19 20 21 22 23 . Our approach is to use strain from piezoelectric transducers to modify the anisotropy in PMA materials and thus reduce the magnetic field needed for domain wall motion.…”

Electric field control of multiferroic domain wall motion

“…Recently, it has been shown that modulating the magnetic anisotropy by an applied electric field is possible, 20,21 and thus will allow for the electric field control of DW dynamics in ultrathin metallic ferromagnets. [22][23][24][25][26][27][28] Nevertheless, the search for alternative schemes allowing fast and energy-efficient DW propagation is of great relevance in advanced spintronics research.…”