Spin transfer stimulated microwave emission in MgO magnetic tunnel junctions

Measurements of noise properties of MgO-based magnetic tunnel junctions were performed in the frequency range from 100 MHz to 18 GHz. A pronounced narrow peak at the frequency of around 7 GHz with a full width at half-maximum as low as 21 MHz has been observed. The peak amplitude and 1/f noise have a threshold dependence on the dc bias current. The narrow peak is present only at one current polarity for an antiparallel orientation of the magnetic layers adjacent to the barrier, which is consistent with spin-momentum transfer theoretical predictions. (c) 2006 American Institute of Physics.