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We reported a systematic study of spin-orbit torque biased magnetic sensors based on NiFe/Pt bilayers through both macro-spin modeling and experiments. The simulation results show that it is possible to achieve a linear sensor with a dynamic range of 0.1-10 Oe, power consumption of 1 μW-1mW, and sensitivity of 0.1-0.5 Ω/Oe. These characteristics can be controlled by varying the sensor dimension and current density in the Pt layer. The latter is in the range of 1 × 105-107 A/cm². Experimental results of fabricated sensors with selected sizes agree well with the simulation results. For a Wheatstone bridge sensor comprising of four sensing elements, a sensitivity up to 0.548 Ω/Oe, linearity error below 6%, and detectivity of about 2.8 nT/vHz were obtained. The simple structure and ultrathin thickness greatly facilitate the integration of these sensors for on-chip applications. As a proof-of-concept experiment, we demonstrate its application in detection of current flowing in an on-chip Cu wire. [ABSTRACT FROM AUTHOR]

Recently, we have demonstrated the presence of spin-orbit torque in FeMn/Pt multilayers which, in combination with the anisotropy field, is able to rotate its magnetization consecutively from 0° to 360° without any external field. Here, we report on an investigation of the static and dynamic magnetic properties of FeMn/Pt multilayers using the combined techniques of magnetometry, ferromagnetic resonance, inverse spin Hall effect, and spin Hall magnetoresistance measurements. The FeMn/Pt multilayer was found to exhibit ferromagnetic properties, and its temperature dependence of saturation magnetization can be fitted well using a phenomenological model by including a finite distribution in Curie temperature due to subtle thickness variations across the multilayer samples. The non-uniformity in static magnetic properties is also manifested in the ferromagnetic resonance spectra, which typically exhibit a broad resonance peak. A damping parameter of around 0.106 is derived from the frequency dependence of ferromagnetic resonance linewidth, which is comparable to the reported values for other types of Pt-based multilayers. Clear inverse spin Hall signals and spin Hall magnetoresistance have been observed in all samples below the Curie temperature, which corroborate the strong spin-orbit torque effect observed previously. [ABSTRACT FROM AUTHOR]

We report on the observation of stable electrical oscillation in Pt/vanadium dioxide (VO2) bilayer strips, in which the Pt overlayer serves the dual purposes of heating up the VO2 and weakening the electric field in the VO2 layer. Systematic measurements in an ultrahigh vacuum nanoprobe system show that the oscillation frequency increases with the bias current and/or with decreasing device dimension. In contrast to most VO2-based oscillators reported to date, which are electrically triggered, current-induced Joule heating in the Pt overlayer is found to play a dominant role in the generation of oscillation in Pt/VO2 bilayers. A simple model involving thermally triggered transition of VO2 on a heat sink is able to account for the experimental observations. The results in this work provide an alternative view of the triggering mechanism in VO2-based oscillators. [ABSTRACT FROM AUTHOR]