We reported microwave measurements on a nanoscale MgO-based magnetic tunnel junction having an elliptical shape with large aspect ratios to obtain enough in-plane shape anisotropy to ensure free layer magnetization along the long axis. Combined with the magnetization of a synthetic antiferromagnet pinned layer along the short axis, this results in the perpendicular configuration between the magnetizations of free and pinned layers. A steady high frequency oscillation up to 5 GHz was achieved in such devices at zero magnetic field. Meanwhile, a large frequency tunability of 0.11 Hz·cm2/mA (2.67 GHz/mA) was obtained. The micromagnetic simulations confirm the origin of the high oscillation frequency of our spin transfer nano-oscillators (STNOs). These results suggest the great possibility of improved integration and potential application of STNOs for developing the next-generation of on-chip oscillators.
Bias-field-free high frequency microwave emission of spin-transfer nano-oscillator with magnetizations all in-plane
W. Zhang, Y. Zhang, B. Jiang, B. Fang, H. Zhong, H. Li, Z. M. Zeng, S. S. Yan, G. Han, G. Liu, S. Yu, S. Kang; Bias-field-free high frequency microwave emission of spin-transfer nano-oscillator with magnetizations all in-plane. Appl. Phys. Lett. 4 January 2021; 118 (1): 012405. https://doi.org/10.1063/5.0031507
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