Scalable Spin-to-Charge Conversion Device with Nanopatterning

Abstract

The innovative spin-to-charge conversion devices, such as magneto-electric spin–orbit (MESO) logic devices, can seamlessly transform spin signals into electrical charge, revolutionizing data processing and storage technologies. The realization of the MESO devices has been hindered by the limited signal response of the ferromagnetic spin state readout via the inverse spin Hall (ISH) effect. This paper presents a novel T-shaped W/CoFeB ISH nanodevice with excellent scalability. In experiments, upscaling the width of the W channel from 400 to 95 nm was shown to enhance the ISH signal intensity by ∼400%. A subsequent reduction in the thickness of the W channel from 13 to 10 nm further enhanced the ISH signal by ∼33%. Note that signal enhancement did not incur an increase in the coercivity. Technology computer-aided design (TCAD) simulation was used to optimize dimension effects in the proposed device. The delicate W/CoFeB intersection in this T-shaped layout was patterned by depositing an ultrathin Cu layer as an alternative to conventional Ar ion-milling. This design approach capitalizes on the small spin-Hall angle of Cu with high spin-diffusion length while preventing milling-induced structural damage to the ISH core structure. Cu insertion reduced the switching coercivity by ∼22% without sacrificing the output ISH signal strength. The proposed nanopatterning process represents a notable step in the development and miniaturization of next-generation spintronic logic devices.