Highly sensitive spin-torque diodes based on in-plane magnetized magnetic tunnel junctions

Abstract

We investigate the highly sensitive spin torque diode (STD) effect in a magnetic tunnel junction (MTJ) with an in-plane polarizer and an in-plane free layer. Under injection locking mechanisms, a high rectification voltage of 12 mV is obtained with an input radio frequency power of 1 μW under direct current bias current and a weak magnetic field, corresponding to a high sensitivity of 12 000 mV/mW. In addition, we use the nonlinear rectification characteristics of STD to mimic a neuron with a ReLU-like activation function to perform the recognition of handwritten digits in the Mixed National Institute of Standards and Technology database, where a produced accuracy of up to 93.53% is obtained. These findings suggest that the MTJ with in-plane magnetized electrodes holds promising potential in developing 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

“…Due to the Co-rich in the free layer, the in-plane magnetic anisotropy will be enhanced, 25,26) compared to the Co 40 Fe 40 B 20 free layer in our previous works. 20) The top MgO (0.7) is the cap layer. The magnetic multilayer stacks are annealed at a temperature of 300 °C for 2.0 h in an in-plane magnetic field of 1 T. Electron beam lithography and ion beam milling are employed to define and etch the MTJ multilayers, yielding elliptical nanopillars.…”

“…In recent years, spintronic devices, which utilize the charge and spin of electrons, have attracted considerable attention due to their improved characteristics and new functional capabilities compared with conventional electronic devices. Among these devices are new types of magnetic sensors, [1][2][3] magnetic random access memories, [4][5][6] microwave neurons, [7][8][9][10] microwave oscillators, 11,12) microwave detectors, [13][14][15][16][17][18][19][20] etc. The latter category of devices, which is based on the spin torque diode (STD) with magnetic tunnel junctions (MTJs), is regarded as one of the most promising spintronic devices.…”

“…24) More recently, we have developed an in-plane MTJ to focus on the STD properties. 20) The in-plane magnetized anisotropy in the free layer is not strong enough to reach a high detection frequency.…”