Enhanced broadband RF detection in nanoscale magnetic tunnel junction by interface engineering.

Abstract

Broadband RF detection is of great interest for its potential applications in wireless charging and energy harvesting. Here, we demonstrate that the bandwidth of broadband 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 MgO tunnel barrier, by adjusting the CoFeB free layer thickness. An ultra-wide RF detection bandwidth of over 3 GHz is observed in the MTJs (> 3× larger than in previous work), and the broadband RF detection behavior can be systematically 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 fields, for free layers with a thickness of about 1.65 nm. Finally, the dependence of broadband RF detection bandwidth on external magnetic field and RF power are discussed. Our results pave the way for RF energy harvesting for future portable nanoelectronics.