High-power coherent microwave emission from magnetic tunnel junction nano-oscillators with perpendicular anisotropy.
The excitation of the steady-state precessions of magnetization opens a new way for nanoscale microwave oscillators by exploiting the transfer of spin angular momentum from a spin-polarized current to a ferromagnet, referred to as spin-transfer nano-oscillators (STNOs). For STNOs to be practical, however, their relatively low output power and their relatively large line width must be improved. Here we demonstrate that microwave signals with maximum measured power of 0.28 μW and simultaneously narrow line width of 25 MHz can be generated from CoFeB-MgO-based magnetic tunnel junctions having an in-plane magnetized reference layer and a free layer with strong perpendicular anisotropy. Moreover, the generation efficiency is substantially higher than previously reported STNOs. The results will be of importance for the design of nanoscale alternatives to traditional silicon oscillators used in radio frequency integrated circuits.
Department of Physics and Astronomy, University of California, Los Angeles, California 90095, United States. zhongming.zeng@gmail.com
Zhongming
Z
Zeng
Pedram Khalili
PK
Amiri
Ilya N
IN
Krivorotov
Hui
H
Zhao
Giovanni
G
Finocchio
Jian-Ping
JP
Wang
Jordan A
JA
Katine
Yiming
Y
Huai
Juergen
J
Langer
Kosmas
K
Galatsis
Kang L
KL
Wang
Hongwen
H
Jiang