Exploration of Interfacial Perpendicular Anisotropy of Magnetic Tunneling Junctions for High Perofrmance Microwave Devices
Research on magnetic tunneling junctions (MTJ) has traditionally and predominantly focused on the properties that are important for magnetic random access memory. However, in the recent few years, it has become increasingly apparent that the exquisite control of high frequency spin dynamics by current or voltage in MTJs can be used to create devices with unique and desirable microwave properties. In particular, the perpendicular magnetic anisotropy (PMA), induced by the hybridization of orbitals between thin ferromagnetic CoFeB film and an MgO insulator, significantly enhance the efficiency of spin torque driven dynamics while allowing device operation in the absence of an external magnetic field. In this talk, I will describe our experimental efforts at UCLA to establish state-of-the-art figure of merits in MTJ microwave devices. Microwave oscillators of frequency as high as 6 GHz, at zero applied field and room temperatures, are realized by using an out-of-plane polarizer, enabled by the PMA. A boost of microwave emission power, in micro-W range, assisted by PMA, has been established. An ultra-high microwave sensitivity of 250,000 V/W has been obtained by optimizing the PMA and using an injection locking mechanism. This sensitivity is significantly larger than both the best Schottky diode detectors and other existing spintronic diodes. The future perspective of possible applications of these microwave devices in neuromorphic computing, high-frequency microwave sensing, and high-speed multiplex telecommunications will be discussed.
|Exploration of Interfacial Perpendicular Anisotropy of Magnetic Tunneling Junctions for High Performance Microwave Devices|
Wednesday, April 5, 2017, 11 a.m.–noon PT
Los Angeles, CA, United States