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In this paper, molecular dynamics simulations are performed on a [10, 10]/[5, 5] carbon nanotube-based oscillator. In our work, we observed a spin phenomenon of the inner tube when it oscillated in an isolated oscillator system. If there exist a rocking motion when the inner tube started to oscillate, an axial torque would be observed, and it would drive the inner tube to spin. When the oscillation became stable, the torque almost vanished, and the spin was stabilized with a constant frequency of 21.78 GHz. Such a spin phenomenon was also observed when the oscillator system was at a room temperature of 300 K. However, both magnitude and direction of the spin angular velocity varied from time to time, even after the oscillation of the inner tube stopped due to the energy dissipation.

Due to the demagnetization field of the free layer, an approximate theory was introduced to analyze the synchronization mechanism of coupled nano-oscillators. The necessary conditions of synchronization for a coupled spin-transfer-torque system are derived and dipolar interaction generates synchronization within an induced corrugated attractor. The theory of corrugated attractor also shows that the current feedback effect from Giant Magnetoresistance (GMR) cannot synchronize the second type of spin-torque nano-oscillators. Our theory is consistent with the numerical results from the Landau–Lifshitz–Gilbert equation with a spin-transfer-torque.

This paper reviews the progress made over the last few years in understanding the development of perpendicular magnetic tunneling junctions (pMTJs). The material systems for making pMTJs, including rare-earth/transition metal alloys, L1₀-ordered (Co, Fe)–Pt alloys, Co/(Pd, Pt) multilayers, and CoFeB–MgO crystallized structures, are briefly introduced. The fabrication processes of the MTJ devices are focused on, consisting of open-trench, etch-back and self-aligned techniques. The authors also propose a spin-torque nano-oscillator based on pMTJ, for application in GHz range telecommunications.

This paper reviews the current status of maximizing output power in spin transfer nano-oscillators (STNOs). The key factors affecting output power and the methods to maximize output power in STNOs are briefly introduced. The recent development trends for STNOs are also reviewed in this paper. This article is one of a series devoted to the subject of Latest Progress on Spintronics Devices.