Magnetic heterostructure Mo/CoFeB/MgO has strong perpendicular magnetic anisotropy and thermal stability. Through current-induced hysteresis loop shift measurements, we show that the dampinglike spin-orbit torque (SOT) efficiency of Mo/CoFeB/MgO heterostructures is 0.003 0.001 DL     and fairly independent of the annealing temperature from 300˚C to 400˚C. Though DL  is small while compare to those from Ta or Wbased heterostructures, reversible current-induced SOT switching of a thermally-stable Mo/CoFeB/MgO heterostruture can still be achieved. Furthermore, we observe field-free current-induced switching from a Mo/CoFeB/MgO structure with the Mo layer being wedge-deposited. Our results indicate that even for a weak spin-orbit interaction 4d transition metal such as Mo, it is still possible to generate sufficient spin current for conventional SOT switching and to realize field-free current-induced switching by structural engineering. 

The spin Hall effect (SHE) is found to be strong in heavy transition metals (HM), such as Ta and W, in their amorphous and/or high resistivity form. In this work, we show that by employing a CuTa binary alloy as buffer layer in an amorphous Cu100-xTax-based magnetic heterostructure with perpendicular magnetic anisotropy (PMA), the SHE-induced damping-like spin-orbit torque (DL-SOT) efficiency DL  can be linearly tuned by adjusting the buffer layer resistivity. Currentinduced SOT switching can also be achieved in these Cu100-xTax-based magnetic heterostructures, and we find the switching behavior better explained by a SOT-assisted domain wall propagation picture. Through systematic studies on Cu100-xTax-based samples with various compositions, we determine the lower bound of spin Hall conductivity

It has been shown that the spin Hall effect from heavy transition metals can generate sufficient spin-orbit torque and further produce current-induced magnetization switching in the adjacent ferromagnetic layer. However, if the ferromagnetic layer has in-plane magnetic anisotropy, probing such switching phenomenon typically relies on tunneling magnetoresistance measurement of nanosized magnetic tunnel junctions, differential planar Hall voltage measurement, or Kerr imaging approaches. We show that in magnetic heterostructures with spin Hall metals, there exist currentinduced in-plane spin Hall effective fields and unidirectional magnetoresistance that will modify their anisotropic magnetoresistance behavior. We also demonstrate that by analyzing the response of anisotropic magnetoresistance under such influences, one can directly and electrically probe magnetization switching driven by the spin-orbit torque, even in micron-sized devices. This pumpprobe method allows for efficient and direct determination of key parameters from spin-orbit torque switching events without lengthy device fabrication processes. †

The spin-orbit torques (SOTs) generated from topological insulators (TIs) have gained increasing attention in recent years. These TIs, which are typically formed by epitaxially grown chalcogenides, possess extremely high SOT efficiencies and have great potential to be employed in the next-generation spintronics devices. However, epitaxy of these chalcogenides is required to ensure the existence of topologically-protected surface state (TSS), which limits the feasibility of using these materials in industry. In this work, we show that non-epitaxial BixTe1-x/ferromagnet heterostructures prepared by conventional magnetron sputtering possess giant SOT efficiencies even without TSS. Through harmonic voltage measurement and hysteresis loop shift measurement, we find that the damping-like SOT efficiencies originated from the bulk spin-orbit interactions of such non-epitaxial heterostructures can reach values greater than 100% at room temperature. We further demonstrate current-induced SOT switching in these BixTe1-x-based heterostructures with thermally stable ferromagnetic layers, which indicates that such non-epitaxial chalcogenide materials can be potential efficient SOT sources in future SOT magnetic memory devices.

Interfacial Dzyaloshinskii-Moriya interaction (DMI) has long been observed in normal metal/ferromagnetic multilayers, enabling the formation of chiral domain walls, skyrmions and other 2D antisymmetric spin textures confined within a single ferromagnetic layer, while more recent works on interlayer DMI reveal new pathways in realizing novel chiral 3D spin textures between two separate layers. Here, we report on interlayer DMI between two orthogonally magnetized ferromagnetic layers (CoFeB/Co) mediated by a Pt layer, and confirm the chiral nature of the observed effective field of up to 37 Oe through asymmetric hysteresis loops under in-plane field. We highlight the importance of growth-induced in-plane symmetry breaking, resulting in a sizable interlayer DMI and a universal characteristic vector through wedge deposition of the samples. We further perform deterministic current-driven magnetization switching in the perpendicularly magnetized Co layer utilizing solely the effective field from the interlayer DMI. These results demonstrate interlayer DMI's potential to facilitate deterministic field-free switching in spin memory applications.