A numerical study of spin torque oscillators based on IMA/PMA bilayer nano-pillars

• Published in: Nanotechnology Vol. 31; no. 34; p. 345709
• Main Authors: Yuan, X, Lu, Z, Li, S, Fan, S, Wang, G, Fang, X, Xiong, R
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 21.08.2020
• Subjects: micro-magnetic simulation; nano-oscillator; spin-transfer torque; STT; nano-oscillator; micro-magnetic simulation
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/1361-6528/ab91f5

In this paper, the magnetization dynamics of bilayer structured nano-pillars containing a fixed layer with perpendicular magnetic anisotropy (PMA) and a free layer with in-plane magnetic anisotropy (IMA) are studied using the micro-magnetic simulation method. Unlike typical sandwich-structured spin-torque nano-pillar oscillators (STNOs), the proposed structure does not contain any nonmagnetic spacer layer. It is found that a stable oscillation with a significant amplitude can be established fast after driving out the vortex core by an in-plane magnetic pulse field. The oscillation frequency and amplitude can be easily manipulated by adjusting the side-length of the nanopillar, the thickness and saturation magnetization of the IMA layer, and an applied magnetic field along z axis. In an array with an adequate inter-pillar distance, the mutual interaction between the nano-pillars will lead the oscillations to be phase-locked, resulting in a considerable enhancement of total amplitude. As it is easy to fabricate these kinds of bi-layer nano-pillars and assemble them in arrays, they may have widespread applications in STNOs.