Nonlinear dynamics has been the key ingredient to improve the performance, in terms of sensitivity, of biased resonant spintronic diodes beyond their semiconductor counterparts. We experimentally demonstrate a nonlinear regime broadband detection for nanoscale spintronic diodes (NSD) where the rectification properties are independent of the input microwave frequency, and compare the device performance with the state of the art Schottky diode for low-power rectification. This regime is achieved in magnetic tunnel junctions with a canted magnetization of the free layer. We further show that the developed NSD provides sufficient dc voltage to supply a low-power nanodevice − a black phosphorus photosensor. Our results could pave the way for using spintronic detectors as building blocks for self-powered nanosystems, such as implantable biomedical devices, wireless sensors, and portable electronics.BIN FANG et al.PHYS. REV. APPLIED 0, XXXXXX (2019) spintronic diodes (NSD) are capable of powering a black phosphorus (BP) photosensor [15][16][17].
The advantage of an ultra-fast frequency-tunability of spin-torque nano-oscillators (STNOs) that have large (> 100MHz) relaxation frequency of amplitude fluctuations is exploited to realize ultra-fast wide-band time-resolved spectral analysis at nanosecond time scale with the frequency resolution limited only by the "bandwidth" theorem. The demonstration is performed with an STNO generating in the 9 GHz frequency range, and comprised of a perpendicular polarizer and a perpendicularly and uniformly magnetized "free" layer. It is shown that such a uniform-state STNO-based spectrum analyzer can efficiently perform spectral analysis of frequency-agile signals with rapidly varying frequency components.
A design of a magnonic phase shifter operating without an external bias magnetic field is proposed. The phase shifter uses a localized collective spin wave mode propagating along a domain wall "waveguide" in a dipolarly-coupled magnetic dot array existing in a chessboard antiferromagnetic (CAFM) ground state. It is demonstrated numerically that remagnetization of a single magnetic dot adjacent to the domain wall waveguide introduces a controllable phase shift in the propagating spin wave mode without significant change of the mode amplitude. It is also demonstrated that a logic XOR gate can be realized in the same system.Comment: 6 pages, 4 figure
A spintronic method of ultra-fast broadband microwave spectrum analysis is proposed. It uses a rapidly tuned spin torque nano-oscillator (STNO), and does not require injection locking. This method treats an STNO generating a microwave signal as an element with an oscillating resistance. When an external signal is applied to this "resistor" for analysis, it is mixed with the signal generated by the STNO. The resulting mixed voltage contains the "sum" and "difference" frequencies, and the latter produces a DC component when the external frequency matches the frequency generated by the STNO. The mixed voltage is processed using a low pass filter to exclude the "sum" frequency components, and a matched filter to exclude the dependence of the resultant DC voltage on the phase difference between the two signals. It is found analytically and by numerical simulation, that the proposed spectrum analyzer has a frequency resolution at a theoretical limit in a real-time scanning bandwidth of 10 GHz, and a frequency scanning rate above 1 GHz/ns, while remaining sensitive to signal power as low as the Johnson-Nyquist thermal noise floor.Spectrum analyzers are critically important instruments with applications in engineering, science, and medicine 1,2 . Historically, spectrum analyzers have been implemented with either swept-tuned or Fourier methods. More recently, real-time spectrum analyzers have started to use a combination of these methods and vector signal analysis. Despite substantial technological improvements, current real time spectrum analyzers for demanding applications, such as pulsed radar frequency determination or electronic signal intelligence, are exceedingly complex and/or computationally expensive 1 .We propose to use a rapidly tuned spin torque nanooscillator (STNO) 3-7 based on a magnetic tunnel junction (MTJ) to perform fast, broadband spectrum analysis with frequency scanning rates and bandwidths that exceed current state of the art, all while remaining sensitive to signals with power levels as low as the Johnson-Nyquist thermal noise floor. STNOs are nano-sized low power microwave auto-oscillators that can be tuned over a wide frequency range by adjusting a driving bias DC current. They have a number of interesting features, including low operating power, compatibility with CMOS technology, nonlinear synchronization behavior, operation from below 1 GHz to above 65 GHz, high modulation rates, and the possibility of a radiation-hard construction 7-19 . At low frequencies (f < 3 GHz), they have been constructed to operate in the absence of a bias magnetic field 20 . STNO oscillations occur in an MTJ when a DC electric current of sufficient amplia) slouis@oakland.edu tude excites the free layer magnetization to precess with a microwave frequency due to the spin-transfer torque effect 21,22 . These magnetization oscillations can be detected macroscopically through the effect of tunneling magnetoresistance (TMR). For the purposes of this paper, an STNO (a current-driven MTJ with an oscillating TMR) will be tre...
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