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Abstract Unconventional spin‐orbit torques arising from electric‐field‐generated spin currents in anisotropic materials have promising potential for spintronic applications, including for perpendicular magnetic switching in high‐density memory applications. Here, all the independent elements of the spin torque conductivity tensor allowed by bulk crystal symmetries for the tetragonal conductor IrO₂are determined via measurements of conventional (in‐plane) anti‐damping torques for IrO₂thin films in the high‐symmetry (001) and (100) orientations. It is then tested whether rotational transformations of this same tensor can predict both the conventional and unconventional anti‐damping torques for IrO₂thin films in the lower‐symmetry (101), (110), and (111) orientations, finding good agreement. The results confirm that spin‐orbit torques from all these orientations are consistent with the bulk symmetries of IrO₂, and show how simple measurements of conventional torques from high‐symmetry orientations of anisotropic thin films can provide an accurate prediction of the unconventional torques from lower‐symmetry orientations. 

Abstract Spin–orbit torques generated by a spin current are key to magnetic switching in spintronic applications. The polarization of the spin current dictates the direction of switching required for energy‐efficient devices. Conventionally, the polarizations of these spin currents are restricted to be along a certain direction due to the symmetry of the material allowing only for efficient in‐plane magnetic switching. Unconventional spin–orbit torques arising from novel spin current polarizations, however, have the potential to switch other magnetization orientations such as perpendicular magnetic anisotropy, which is desired for higher density spintronic‐based memory devices. Here, it is demonstrated that low crystalline symmetry is not required for unconventional spin–orbit torques and can be generated in a nonmagnetic high symmetry material, iridium dioxide (IrO₂), using epitaxial design. It is shown that by reducing the relative crystalline symmetry with respect to the growth direction large unconventional spin currents can be generated and hence spin–orbit torques. Furthermore, the spin polarizations detected in (001), (110), and (111) oriented IrO₂thin films are compared to show which crystal symmetries restrict unconventional spin transport. Understanding and tuning unconventional spin transport generation in high symmetry materials can provide a new route towards energy‐efficient magnetic switching in spintronic devices. 

Abstract The prospect of 2‐dimensional electron gases (2DEGs) possessing high mobility at room temperature in wide‐bandgap perovskite stannates is enticing for oxide electronics, particularly to realize transparent and high‐electron mobility transistors. Nonetheless only a small number of studies to date report 2DEGs in BaSnO₃‐based heterostructures. Here, 2DEG formation at the LaScO₃/BaSnO₃(LSO/BSO) interface with a room‐temperature mobility of 60 cm² V⁻¹ s⁻¹at a carrier concentration of 1.7 × 10¹³ cm^–2is reported. This is an order of magnitude higher mobility at room temperature than achieved in SrTiO₃‐based 2DEGs. This is achieved by combining a thick BSO buffer layer with an ex situ high‐temperature treatment, which not only reduces the dislocation density but also produces a SnO₂‐terminated atomically flat surface, followed by the growth of an overlying BSO/LSO interface. Using weak beam dark‐field transmission electron microscopy imaging and in‐line electron holography technique, a reduction of the threading dislocation density is revealed, and direct evidence for the spatial confinement of a 2DEG at the BSO/LSO interface is provided. This work opens a new pathway to explore the exciting physics of stannate‐based 2DEGs at application‐relevant temperatures for oxide nanoelectronics.