Stabilization of exponential number of discrete remanent states with localized spin-orbit torques

Abstract

Using bilayer films of $\beta$-Ta/Ni${}_{0.8}$Fe${}_{0.2}$, we fabricate structures consisting of two, three and four crossing ellipses which exhibit shape-induced bi-axial, tri-axial and quadro-axial magnetic anisotropy in the crossing area, respectively. Structures consisting of N crossing ellipses can be stabilized in 2N remanent states by applying (and removing) an external magnetic field. However, we show that with field-free spin-orbit torques induced by flowing currents in individual ellipses, the number of remanent states grows to 2${}^{\text{N}}$. Furthermore, when the current flows between the edges of different ellipses the number of remanent states jumps to 2${}^{\text{2N}}$, including states which exhibit a $\pi$-Néel domain wall in the overlap area. The very large number of accessible remanent magnetic states that are exhibited by the relatively simple magnetic structures paves the way for intriguing spintronics applications including memory devices.

arXiv comment5 pages, 4 Figures; The following article has been accepted by Applied Physics Letters. After it is published, it will be found at https://aip.scitation.org/journal/apl

References in corpus (17)

• Spin torque switching with the giant spin Hall effect of tantalum
• The design and verification of Mumax3
• Magnetic switching by spin torque from the spin Hall effect
• Current-driven dynamics of chiral ferromagnetic domain walls
• Blowing Magnetic Skyrmion Bubbles
• Spin transfer torque devices utilizing the giant spin Hall effect of tungsten
• Spin Transfer Torques in MnSi at Ultra-low Current Densities
• Switching of perpendicular magnetization by spin-orbit torques in the absence of external magnetic fields
• Domain wall motion governed by the spin Hall effect
• Evidence for reversible control of magnetization in a ferromagnetic material via spin-orbit magnetic field
• Spin-orbit torques induced by interface-generated spin currents
• Room-temperature current-induced generation and motion of sub-100nm skyrmions
• Field-free deterministic ultra fast creation of skyrmions by spin orbit torques
• Nanosecond-timescale low error switching of in-plane magnetic tunnel junctions through dynamic Oersted-field assisted spin-Hall effect
• The domain wall spin torque-meter
• Self-current induced spin-orbit torque in FeMn/Pt multilayers
• Quasistatic and Pulsed Current-Induced Switching with Spin-Orbit Torques in Ultrathin Films with Perpendicular Magnetic Anisotropy

Cited by in corpus (1)

• A four-state magnetic tunnel junction switchable with spin-orbit torques