Spin-Torque Assisted Microwave Detectors
- Author(s): Zhang, Jieyi
- Advisor(s): Krivorotov, Ilya
- et al.
This master dissertation investigates detection of microwave signals by magnetic tunnel junctions(
MTJs) as sensing elements. The detection is based on the spin-torque diode eect.
First, we show a wireless detection of microwave signals using a MTJ based detector. This
MTJ detector is integrated with compact coplanar waveguide antennas and non-magnetic,
microwave-transparent, reusable antenna holder. We compare the experimental results with
MTJs of dierent magnetic layer structures. The tested structures can achieve comparable
sensitivities to those of commercial semiconductor, diode-based microwave sensors. The detection
frequencies can be tuned by a permanent magnet attached to the detector. Second,
we demonstrate a microwave frequency determination method by a pair of MTJs as microwave
detectors. A resonance-type spin-torque microwave detector (STMD) can be used
to determine the frequency of an input microwave signal. But the accuracy is limited by
the STMD's ferromagnetic resonance linewidth. By applying a pair of uncoupled STMDs
connected in parallel to a microwave signal source, we show that the accuracy of frequency
measurement is improved signicantly.