CMOS compatible W/CoFeB/MgO spin Hall nano-oscillators with wide frequency tunability

TL;DR

This paper reports on CMOS-compatible W/CoFeB/MgO spin Hall nano-oscillators with record high spin Hall angle and wide frequency tunability, suitable for integrated microwave applications.

Contribution

Demonstration of low-current, CMOS-compatible spin Hall nano-oscillators with wide frequency range and high spin Hall angle on resistive silicon substrates.

Findings

Achieved a threshold current density of 3.3×10^7 A/cm^2

Frequency tunability from 7 to 28 GHz

High spin Hall angle of -0.53 in β-phase W

Abstract

We demonstrate low-operational-current W/Co$_{20}$Fe$_{60}$B$_{20}$/MgO spin Hall nano-oscillators (SHNOs) on highly resistive silicon (HiR-Si) substrates. Thanks to a record high spin Hall angle of the $\beta$-phase W ($\theta_{SH}$ = -0.53), a very low threshold current density of 3.3 $\times$ 10$^{7}$ A/cm$^2$ can be achieved. Together with their very wide frequency tunability (7-28 GHz), promoted by a moderate perpendicular magnetic anisotropy, this makes HiR-Si/W/CoFeB based SHNOs potential candidates for wide-band microwave signal generation. Their CMOS compatibility offers a promising route towards the integration of spintronic microwave devices with other on-chip semiconductor microwave components.