Spin-torque quantization and microwave sensitivity of a nano-sized spin diode

Abstract

Rectification of microwave signal by the spin-torque diode is very promising for its practical applications in microwave imaging. This is due to a very high sensitivity of magnetic tunnel junction under the bias current, which was previously demonstrated in a number of works [1-3]. The decreasing of cross-sectional area of the spin-torque diode up to the nano-sized dimensions below 10 nm allows one to reach high sensitivity without any bias current. Transverse quantization of electron states in the magnetic nanowire based on nano-sized metallic spin valves and magnetic tunnel junctions can create an additional impact not only on the magnetoresistance, but also on the spin-transfer torque in such structures. In this work we present an analysis of the quantization effect of conductance and spin-transfer torques on the microwave sensitivity of nano-sized spin-torque diodes during the reduction of its cross-sectional area. It was found that the magnetoresistance values up to 130 % can be achieved in a magnetic nanowire containing spin-valve diode with the nonmagnetic metal spacer. As a result, the maximum microwave sensitivity of spin-torque diodes based on these structures can be increased several times that opens the way for the further development of highly sensitive microwave detectors.

Spin Diode Based Microwave Registration and Holographic Visualization of Wave Front Scattering for an Autonomous Driving System

“…Other physical mechanisms of spin systems response discussed in [18,19]. Spin diodes with a noncollinear spin configuration of adjacent magnetic layers of the tunnel junction under resonant excitation of spin vibrations due to current transfer of rotational moment in the presence of a bias current near and above the boundary of micromagnetic instability have the highest microwave sensitivity to microwave irradiation [4,17,[20][21][22]. We calculated the resonance dependence of the microwave sensitivity of the spin diode based on the Landau -Lifshitz equations modified by Slonczewski, for several values of the bias current [20].…”

“…In this work, we study the potential of the method of holographic detection and visualization of objects using highly sensitive spin diodes. Those diodes possess advantages at low microwave irradiation power [3][4][5][6][20][21][22] and can show a significantly higher sensitivity than the sensitivity of a Schottky diode at a similar level of equivalent input noise [16]. Estimates show that for a specified sensitivity, taking into account the radiation safety standards, there exists at least 25 m safe obstacle detection range.…”