Enhancing Frequency and Reducing the Power of Spin-Torque Nanooscillator By The Generated Oersted Field

Abstract

The current-driven magnetization precession dynamics stimulated by Spin-Transfer Torque (STT) in a trilayer spin-valve device (typically Spin-Torque Nanooscillator (STNO)) is numerically investigated by solving the Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation. We have devised four STNO devices made of ferromagnetic alloys such as CoPt, CoFeB, Fe[Formula: see text]B[Formula: see text]Ni2 and EuO, which act as free and fixed layers. Here, copper acts as a nonmagnetic spacer for all the devices. In this work, we have introduced the current-induced Oersted field, which is generated when a spin-polarized current passes through the device. The generated Oersted field strength is varied by increasing the diameter of the STNO device. Frequency tunability is achieved in all the four devices, whereas the power of the individual device reduces. The frequency and power of the devices depend entirely on the saturation magnetization of the material, which inherently reflects in the current density and the coherence of the spin-polarized DC. In all devices, the frequency increases, whereas the power decreases by increasing the strength of the Oersted field. Among the four devices, the maximum frequency can be tuned up to 104[Formula: see text]GHz with 40[Formula: see text]nm device diameter, which is obtained for EuO material. This opens a promising source and paves a glittering future for the nanoscale spintronic devices.