Microwave holography using a magnetic tunnel junction based spintronic microwave sensor

Fu, Lei; Gui, Y. S.; Bai, Lihui; Guo, Hong; Abou‐Rachid, Hakima; Hu, C.‐M.

doi:10.1063/1.4921887

Cited by 14 publications

(7 citation statements)

References 23 publications

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“…This provides a promising approach for microwave imaging, which can be potentially applied in biomedical devices. Moreover, in the work by Fu et al., [ 77 ] an STD‐based RF holographic imaging system was developed, demonstrating the feasibility of RF holographic imaging applications using STD. It was demonstrated that high sensitivity of the RF phase measurement leads to the coherent reconstructed target imaging in noise environments.…”

Section: Std's Applicationsmentioning

confidence: 99%

Spin‐Torque Diodes: From Fundamental Research to Applications

Skirdkov

Zvezdin

2020

Annalen der Physik

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Among a rich variety of emerging spintronic devices, spin‐torque diodes (STDs) are among the most interesting, from both a fundamental and an applied perspective. The spin‐torque diode effect occurs when a microwave alternating electric current injected into a magnetic tunneling junction (MTJ) is rectified due to the simultaneous actions of tunneling magnetoresistance and spin‐transfer torque. While the sensitivity of STDs observed in the initial research is rather modest (about 1.4 mV mW−1), after only a few years researchers have increased it to 200 kV W−1 and demonstrated rectification at nanowatt input powers, which radically exceeds the capabilities of mainstream Schottky diodes. This impressive progress is based on a deep understanding of the complex STD physics and on recent advances in MTJ fabrication technology. Herein, the experimental pathways toward increasing the sensitivity and extending the frequency range of STDs and theoretical works aimed at explaining the complex nonlinear dynamics are analysed, and a wide variety of possible STD applications are discussed.

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Section: Std's Applicationsmentioning

confidence: 99%

Spin‐Torque Diodes: From Fundamental Research to Applications

Skirdkov

Zvezdin

2020

Annalen der Physik

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Zvezdin¹,

Leshchiner²,

Popkov³

et al. 2020

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In the paper, we discuss the scheme and the prospects of holographic visualization for microwave scattering objects. At the core of our method is microwave registrationbased on spin diodes, to identify obstacles to the movement for the car's autonomous driving system. The resolution of the holographic system grows with wavelength decrease. However, the recording capacity at a given level of irradiating signal and diode noise decreases. We give an algorithm for the numerical reconstruction and visualization of obstacles. Estimates for the resolution and the reliability of object identification, depending on the distance to the obstacle, obtained by numerical modeling. We show that there is an optimal wavelength to reach the maximum distance of microwave recording, taking into account the system resolution and the acceptable signal level. Highly sensitive spin diodes, feasible for the 2-30 cm wavelength range, nearly approach the optimum range, which is ~ 0.5-1 cm for Schottky diodes, in their holographic visualization ability. Based on the Kotelnikov theorem for the sampling frequency of a harmonic signal, and on numerical experiments, the requirements for the placement density of the receiving elements of the recorder antenna array were determined depending on the distance to the object, the number of sensors and the recording window size. We show that a microwave-recording device based on spin diodes can be promising for an autonomous driving system in conditions of constrained movement with poor visibility and high noise.

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“…, where in P is the input microwave power, can exceed the sensitivity of a semiconductor Schottky diode by an order of value in the presence of the bias current [2][3][4]. High effect of the rectification of the microwave signal in MTJ makes spintorque diode attractive for practical applications in the microwave vision techniques [5]. However, the threshold current density, in the vicinity of which there is a sharp increase in the spin-torque diode sensitivity, is generally high.…”

Section: Introductionmentioning

confidence: 99%

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

Demin

Popkov

2018

EPJ Web Conf.

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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.

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Microwave holography using a magnetic tunnel junction based spintronic microwave sensor

Cited by 14 publications

References 23 publications

Spin‐Torque Diodes: From Fundamental Research to Applications

Spin‐Torque Diodes: From Fundamental Research to Applications

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

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

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