Observation of room-temperature magnetic skyrmions and their current-driven dynamics in ultrathin metallic ferromagnets

Abstract

Magnetic skyrmions are topologically protected spin textures that exhibit fascinating physical behaviours and large potential in highly energy-efficient spintronic device applications. The main obstacles so far are that skyrmions have been observed in only a few exotic materials and at low temperatures, and fast current-driven motion of individual skyrmions has not yet been achieved. Here, we report the observation of stable magnetic skyrmions at room temperature in ultrathin transition metal ferromagnets with magnetic transmission soft X-ray microscopy. We demonstrate the ability to generate stable skyrmion lattices and drive trains of individual skyrmions by short current pulses along a magnetic racetrack at speeds exceeding 100 m s(-1) as required for applications. Our findings provide experimental evidence of recent predictions and open the door to room-temperature skyrmion spintronics in robust thin-film heterostructures.

Shapiro steps for skyrmion motion on a washboard potential with longitudinal and transverse ac drives

“…In contrast, the skyrmions that were recently discovered in chiral magnets have particle-like properties and many similarities to superconducting vortices, but have the important distinction that there is a strong non-dissipative Magnus force in their motion [36][37][38][39][40][41][42][43][44][45] . The skyrmions can be set into motion by an applied current and are observed to have a very small depinning threshold [38][39][40][41]46,47 , in part because the effectiveness of the Magnus force can be up to ten times stronger than the dissipative force component.…”

Chiral magnetoresistance in Pt/Co/Pt zigzag wires

“…Apart from the chiral behavior of the conduction spins, the chiral nature of localized spins has recently been discovered in ferromagnetic materials with inversion asymmetry and SOC. This gives rise to the Dzyaloshinskii-Moriya interaction (DMI) [3,4] leading to a chiral spin texture of the localized spins (C m ), manifested as Néel type magnetic domain walls (DWs) [5] and magnetic skyrmions [6], which are crucial to the future design of spintronic devices.Although these two effects originate in different spin systems, one can speculate about their interplay through exchange interaction between the conduction and localized spins [7][8][9]. This results in a magnetoresistance (MR) which arises when the conduction electron spins propagate with a fixed chirality due to Rashba-type SOC and interact with the chiral DMI-induced magnetic texture.…”

“…Apart from the chiral behavior of the conduction spins, the chiral nature of localized spins has recently been discovered in ferromagnetic materials with inversion asymmetry and SOC. This gives rise to the Dzyaloshinskii-Moriya interaction (DMI) [3,4] leading to a chiral spin texture of the localized spins (C m ), manifested as Néel type magnetic domain walls (DWs) [5] and magnetic skyrmions [6], which are crucial to the future design of spintronic devices.…”

Emergent geometric frustration of artificial magnetic skyrmion crystals

“…The presence and nucleation of individual/isolated skyrmions in confined magnetic nanostructures as well as the evolution of the skyrmion size has also been demonstrated in circular dots [13,[15][16][17][18]74] and nanowires [15,16].…”

“…Pt/CoB/Pt [13], Pt/Co/Ta [15], Pt/CoFeB/MgO [15], Ir/Co/Pt [16], Pt/Co/MgO [17], and Ir/Fe/Co/Pt [18]. Furthermore, the presence and nucleation of individual/isolated skyrmion in confined magnetic nanostructures as well as the evolution of the skyrmion size has also been demonstrated in circular dots [13,[15][16][17][18] and nanowires [15,16].…”