Zero-field dynamics stabilized by in-plane shape anisotropy in MgO-based spin-torque oscillators


Zero-field dynamics stabilized by in-plane shape anisotropy in MgO-based spin-torque oscillators

Kowalska, E.; Kákay, A.; Fowley, C.; Sluka, V.; Lindner, J.; Fassbender, J.; Deac, A. M.

Here, we demonstrate numerically that shape anisotropy in MgO-based spin-torque nano-oscillators consisting of an out-of-plane magnetized free layer and an in-plane polarizer is necessary to stabilize out-of-plane magnetization precession without the need of external magnetic fields. As the in-plane anisotropy is increased, a gradual tilting of the magnetization towards the in-plane easy direction is introduced, favouring zero-field dynamics over static in-plane states. Above a critical value, zero-field dynamics are no longer observed. The optimum ratio of in-plane shape to out-of-plane uniaxial anisotropy, for which large angle out-of-plane zero-field dynamics occur within the widest current range, is reported.

Keywords: spin-torque nano-oscillator (STNO); MgO-based magnetic tunnel junctions; tunnel magnetoresistance (TMR); spin dynamics

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Permalink: https://www.hzdr.de/publications/Publ-28927
Publ.-Id: 28927