Broad-band
radio frequency (RF) detection is of great interest
for its potential applications in wireless charging and energy harvesting.
Here, we demonstrate that the bandwidth of broad-band RF detection
in spin-torque diodes based on magnetic tunnel junctions (MTJs) can
be enhanced through engineering the interface perpendicular magnetic
anisotropy (PMA) between the CoFeB free layer and the MgO tunnel barrier.
An ultrawide RF detection bandwidth of over 3 GHz is observed in the
MTJs, and the broad-band RF detection behavior can be modulated by
tuning the free layer PMA. Furthermore, a wide RF detection bandwidth
(about 1.8 GHz) can be realized even without any external bias field
for free layers with a thickness of about 1.65 nm. Finally, the dependence
of the broad-band RF detection bandwidth on external magnetic field
and RF power is discussed. Our results pave the way for RF energy
harvesting for future portable nanoelectronics.
Flexible electronics or hybrid electronics exhibit great potential for widespread applications in future wearable electronics. In this work, we fabricated flexible nanoscale MgO-barrier magnetic tunnel junctions (MTJs) using a transfer printing process. The magnetic transport measurements reveal that the fabricated devices possess excellent performance with a tunnel magnetoresistance ratio of ∼130% under different strained conditions. In addition, we also studied the spin-torque diode effect under different strained conditions and found that the resonant frequency and rectified voltage remain almost unchanged. These results demonstrate that the nanoscale MTJs have good strain endurance, which provides the feasibility to flexible spintronic storage and microwave applications.
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