We report an approach to improving the performance of spin torque nano-oscillators (STNOs) that utilizes power-dependent negative feedback to achieve a significantly enhanced dynamic damping. In combination with a sufficiently slow variation of frequency with power this can result in a quasi-linear STNO, with very weak non-linear coupling of power and phase fluctuations over a range of bias current and field. An implementation of this approach that utilizes a non-uniform spin-torque demonstrates that highly coherent room temperature STNOs can be achieved while retaining a significant tunability.
@article{arxiv.1306.4668,
title = {A quasi-linear spin-torque nano-oscillator via enhanced negative feedback of power fluctuations},
author = {O. J. Lee and P. M. Braganca and V. S. Pribiag and D. C. Ralph and R. A. Buhrman},
journal= {arXiv preprint arXiv:1306.4668},
year = {2015}
}