Control of skyrmion chirality in Ta/FeCoB/TaOx trilayers by TaOx oxidation and FeCoB thickness

Abstract

Skyrmions are magnetic bubbles with nontrivial topology envisioned as data bits for ultrafast and power-efficient spintronic memory and logic devices. They may be stabilized in heavy-metal/ferromagnetic/oxide trilayer systems. The skyrmion chirality is then determined by the sign of the interfacial Dzyaloshinskii-Moriya interaction (DMI). Nevertheless, for apparently identical systems, there is some controversy about the DMI sign. Here, we show that the degree of oxidation of the top interface and the thickness of the ferromagnetic layer play a major role. Using Brillouin light-scattering measurements in Ta/Fe-Co-B/TaOx trilayers, we demonstrate a sign change of the DMI with the degree of oxidation of the Fe-Co-B/TaOx interface. Using polar magneto-optical Kerr effect microscopy, we consistently observe a reversal of the direction of current-induced motion of skyrmions with the oxidation level of TaOx; this is attributed to their chirality reversal. In addition, a second chirality reversal is observed when changing the Fe-Co-B thickness, probably due to the proximity of the two Fe-Co-B interfaces in the ultrathin case. By properly tuning the chirality of the skyrmion, spin-transfer and spin-orbit torques combine constructively to enhance the skyrmion velocity. These observations thus allow us to envision an optimization of the material parameters to produce highly mobile skyrmions. Moreover, this chirality control enables a versatile manipulation of skyrmions and paves the way towards multidirectional devices.

arXiv comment26 pages, 3 figures

References in corpus (23)

• Skyrmion Lattice in a Chiral Magnet
• Advances in the Physics of Magnetic Skyrmions and Perspective for Technology
• Current-driven dynamics of chiral ferromagnetic domain walls
• Observation of room temperature magnetic skyrmions and their current-driven dynamics in ultrathin Co films
• Direct Observation of the Skyrmion Hall Effect
• Additive interfacial chiral interaction in multilayers for stabilization of small individual skyrmion at room temperature
• Skyrmions at room temperature : From magnetic thin films to magnetic multilayers
• Room temperature chiral magnetic skyrmion in ultrathin magnetic nanostructures
• Current-induced skyrmion dynamics in constricted geometries
• Skyrmion Lattice in a Doped Semiconductor
• Interface control of the magnetic chirality in CoFeB|MgO heterosctructures with heavy metal underlayers
• Room-temperature current-induced generation and motion of sub-100nm skyrmions
• Full phase diagram of isolated skyrmions in a ferromagnet
• Thickness dependence of the interfacial Dzyaloshinskii-Moriya interaction in inversion symmetry broken systems
• Interfacial Dzyaloshinskii-Moriya interaction in perpendicularly-magnetized Pt/Co/AlO${}_x$ ultrathin films measured by Brillouin light spectroscopy
• Large voltage tuning of Dzyaloshinskii-Moriya Interaction: a route towards dynamic control of skyrmion chirality
• Chirality from interfacial spin-orbit coupling effects in magnetic bilayers
• Chirality-induced asymmetric magnetic nucleation in Pt/Co/AlOx ultrathin microstructures
• Interfacial Control of Dzyaloshinskii Moriya Interaction in Heavy Metal_Ferromagnetic Metal Thin Film Heterostructures
• Magnetic skyrmions in confined geometries : effect of the magnetic field and the disorder
• Modification of Dzyaloshinskii-Moriya interaction stabilized domain wall chirality by driving currents
• Dependence of Dzyaloshinskii-Moriya interaction on the oxygen coverage in Pt/Co/MOx trilayers
• Mapping different skyrmion phases in double wedges of Ta/FeCoB(tFeCoB)/Ta(tTa)Ox