The dynamics of a spin-torque-oscillator (STO) coupled with a nano-magnet through dipole-dipole interaction was studied numerically by using the macrospin model for the application of the STO as a read head sensor of hard disk drives. We found that the current, which is required to induce the oscillation of the free-layer (FL) of the STO, depends strongly on the distance between the FL and the nano-magnet as well as on the relative orientation of the magnetizations between them. To determine the dynamics of the STO it is indispensable to consider the dynamics of the dipole-coupled nano-magnet. We showed that we could detect the orientation of the magnetization of a nano-magnet, or a recording-bit, by the modulation of the oscillation frequency of the STO.
@article{arxiv.1301.6458,
title = {Theoretical study of spin-torque oscillator coupled with a nano-magnet by dipole-dipole interaction},
author = {H. Arai and T. Taniguchi and H. Imamura},
journal= {arXiv preprint arXiv:1301.6458},
year = {2013}
}