Spin-torque oscillators using perpendicular anisotropy in CoFeB–MgO magnetic tunnel junctions

A new class of magnetic tunnel junctions (MTJ) with perpendicular anisotropy has been recently used for fast switching applications. A theoretical investigation for these materials to be applied as microwave nano-oscillators is here reported. We demonstrate micro-magnetically the possibility to have both high frequency and high power microwave emission at zero field in a double magnetic tunnel junction. Our predictions give rise to the design of a more compact and easily embedded spin-torque oscillators for all-on-chip applications. To increase the oscillator power, we also demonstrate the possibility to obtain frequency locking at zero field by applying a low current at microwaves.