Ultralow-current density spin-torque diodes with high sensitivity

Abstract

Spin-torque diodes (STDs) offer the possibility of using spin torque to generate rectification voltage with promising applications in microwave detecting, energy harvesting, and neuromorphic computing. Here, we demonstrate a highly sensitive STD with ultralow current density based on a magnetic tunnel junction with perpendicular magnetic anisotropy. At zero magnetic field, a high sensitivity exceeding 3785 V/W is obtained with a low current of −20 μA, corresponding to a current density of ∼105 A/cm2, which is one order lower than the previously reported. When a weak external magnetic field is applied, the sensitivity can be further increased by five times to 20 000 V/W. Furthermore, we construct an artificial neural network with STD neurons to perform recognition of handwritten digits in the Mixed National Institute of Standards and Technology database, where a produced accuracy of up to 94.92% is obtained. Our work provides a route to develop low-power consumption high-sensitivity STDs for Internet of Things applications and neuromorphic computing.

High-frequency ultra-sensitive spin-torque diode based on Co-rich magnetic tunnel junction with in-plane magnetized free layer

“…At the same time, if the frequency of the RF current applied to the MTJ is close to the precession frequency of the free layer, the injection locking will occur and the device will generate high rectification voltage. 15,22,27) Figure 2(a) indicates the dc bias current dependence of the device resistance under the optimum fields of H ext = −200 Oe. It can be seen that with the current increasing, the resistance of the device arrives at an IR state under a certain current range, which indicates that this device can achieve high microwave detection sensitivity through the injection phase locking mechanism.…”

Suppressing Carbon Incorporation in Metal–Organic Chemical Vapor Deposition GaN Using High‐Offcut‐Angled Substrates

“…The growth rates were extracted based on the thicknesses extracted from the SIMS samples and the growth time for each sublayer of the SIMS stack. [11] 0.3°LA-MOCVD GR [μm h À1 ] [11] 4 °C-MOCVD GR comparisons were evaluated using a field-emission gun (FEG)scanning electron microscopy (SEM) (Thermo Scientific Apreo FEG-SEM). To quantitatively analyze the concentrations of impurities incorporated within the GaN films grown at different growth conditions, quantitative SIMS depth profiling was carried out for Si, O, C, and H impurities.…”

“…[8,10] Previous studies have shown that C incorporation increases more significantly when the growth rates are above 5 μm h À1 . [8,11] A theoretical model has been developed to correlate the impurity C incorporation against GaN growth rate, which suggests that C incorporation can be significantly suppressed using GaN substrates with higher offcut angles. [11] In addition, prior studies of GaN films grown on m-plane GaN substrates have shown a reduction in C incorporation with an offcut angle of 5°toward the -c direction.…”

“…[8,11] A theoretical model has been developed to correlate the impurity C incorporation against GaN growth rate, which suggests that C incorporation can be significantly suppressed using GaN substrates with higher offcut angles. [11] In addition, prior studies of GaN films grown on m-plane GaN substrates have shown a reduction in C incorporation with an offcut angle of 5°toward the -c direction. [12,13] The utilization of substrates with increased offcut angles toward the m-plane (from 0°to 6.30°) has also demonstrated reduction in impurity incorporation for GaN films grown on N-polar GaN substrates.…”

“…[20] The reduction in C incorporation in LA-MOCVD GaN has proven to be extremely effective, with suppression in C concentrations ([C]) of up to 87%. [11] From the prior theoretical studies on C suppression using high-offcut-angle GaN substrates and experimental demonstration on the effective suppression of C in LA-MOCVD GaN, it is promising to greatly reduce C incorporation in MOCVD GaN using the combination of LA-MOCVD growth technique and GaN substrates with high offcut angles.…”