Current-induced motion of antiskyrmions in Heusler thin films

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Magnetic skyrmions and antiskyrmions are topologically protectedchiral magnetic nano-objects, which are potential information carriersfor future dense and energy-efficient racetrack memory devices. Inthe first round of this SPP, by employing Lorentz transmission electronmicroscopy (LTEM) and magnetic force microscopy (MFM), weshowed the thickness-independent intrinsic stability of antiskyrmions,robust tunability of the size of antiskyrmions and stabilization ofelliptical Bloch skyrmions in the antiskyrmions system due to longrangedipole-dipole interactions. To date, we have found no evidencefor the motion of antiskyrmions using volume spin transfer torques inlamellae formed from bulk crystals. Our current proposal focuses onthe growth of ultra-thin epitaxial Heusler films that could hostantiskyrmions and from which we can prepare magnetic racetrackswith the principle objective of demonstrating the current-inducedmanipulation of antiskyrmions using spin-orbit torques from adjacentheavy metal layers. To achieve this objective we will explore thegrowth of ultra-thin Heusler films using novel chemical templatinglayers (CTL). The latter have been used to form binary tetragonalcompounds, which are chemically ordered even for room temperaturedeposition. The CTL method uses compounds such as CoAl, IrAl andother members of this family (as an underlayer) with the CsClstructure that are atomically ordered. Our initial focus will be tostabilize individual antiskyrmions in thicker D2d Heusler films. Ournext focus will be to demonstrate the formation of antiskyrmions inultra-thin films, just one or two unit cells thick and exploring the motionof antiskyrmions under spin orbit torques. An important objective willbe to grow Heusler-based synthetic antiferromagnetic (SAF)structures, where two perpendicularly magnetized ferromagneticHeusler sub-layers are coupled via antiferromagnetic interlayerexchange interaction mediated by ultrathin metallic RuAl spacer layer.Unlike antiskyrmions in ferromagnetic materials, coupledantiskyrmions in SAFs are completely free from the influence of theskyrmion Hall effect. To grow these films magnetron co-sputtering, aswell as a low pressure, ion beam sputtering capability with threesources and multiple targets will be employed that has recently beendesigned and built at the MPI-Halle. A combination of variousmagnetic imaging techniques including variable temperatures LTEM,MFM, STXM and Kerr microscopy will be used to study the currentinducedmotion.