The ongoing quest for high density and high speed nanomagnetic computing devices has led to the exploration of novel materials, devices and switching strategies. A topologically protected spiral spin structure called skyrmion has attracted attention due to its potential use as such devices. Skyrmions were first proposed to explain hadrons. Later theories predicted the existence of magnetic skyrmions in the chiral helimagnets. Subsequently, experiments showed the evidence of skyrmion lattices in bulk and thin film. Dzyaloshinskii-Moriya interaction (DMI) that is present in non-centrosymmetric magnets or thin films interface with a metal with large spin orbit coupling, stabilizing the skyrmion state. Several schemes have been investigated to design racetrack memories and logic gates by manipulating the motion of a nonstationary skyrmion because the pinning current is orders of magnitude less than that of domain walls. Core reversal induced by microwave, magnetic field, spin current, and conversion between Skyrmion and ferromagnetic state using Scanning Tunneling Microscope tip and combination of electrical and magnetic fields have been shown.
US 2016/0314827A1, titled “A Memory Device, Comprising at Least One Element and Associated Method Spintronics,” describes a memory device comprising a spintronic element having states associated with sets of magnetic skyrmions. The generation and the stabilization of a set of magnetic skyrmions is produced by either local application of a spin-polarized current or by applying a local electric field. A local magnetic field is applied to allow stabilization of the skyrmions.
WO 2016/158230A1, titled “Skyrmion generation device, skyrmion generation method, and magnetic memory device,” describes applying an electric field to an insulating thin film magnetic body while a magnetic field is also applied.
WO 2016/002806A1, titled “Magnetic Element, Skyrmion Memory, Solid-State Electronic Device, Data Recording Device, Data Processor and Communication Device,” describes a skyrmion memory circuit in which a current is applied in a closed-channel shaped magnetic body, the skyrmions transfer in direction perpendicular to the direction of the applied current, and the skyrmions are caused to circle within the closed-channel shaped magnetic body.
US 2011/0261602A1, titled “Magnetic Memory Devices and Systems,” describes storing bits of information encoded in a topology of a domain wall of a magnetic bubble. The reference discusses providing stable magnetic bubbles with high perpendicular anisotropy structures such as nano-dots and without a need for an additional external bias field. The value of the bit stored by a magnetic bubble is changed by applying a magnetic field gradient pulse or an electrical current excitation.
The above described references, among others, tend to require moving skyrmions which have large footprints, spin currents to switch states which have relatively large energy dissipations, or external magnetic fields to stabilize skyrmions which add complexity and size. These and other disadvantages of existing devices and methods promote the need for novel skyrmion based memory, logic and neuromorphic devices.