All-Electrical Spin Field Effect Transistor in van der Waals Heterostructures at Room Temperature

TL;DR

This paper demonstrates an all-electrical spin field-effect transistor operating at room temperature using a van der Waals heterostructure of graphene and MoS₂, enabling control of spin polarization and lifetime through gate tuning.

Contribution

It introduces the first room-temperature all-electrical spin-FET in a graphene/MoS₂ heterostructure, showcasing electrical control of spin transport and spin lifetime.

Findings

Electrical gate control of spin valve signals at room temperature

Observation of Hanle spin precession in graphene/MoS₂ heterostructure

Spin polarization and lifetime tunable via Schottky barrier modulation

Abstract

Spintronics aims to exploit the spin degree of freedom in solid state devices for data storage and information processing technologies. The fundamental spintronic device concepts such as creation, manipulation and detection of spin polarization has been demonstrated in semiconductors and spin transistor structures using both the electrical and optical methods. However, an unsolved challenge in the field is the realization of all electrical methods to control the spin polarization and spin transistor operation at ambient temperature. For this purpose, two-dimensional (2D) crystals offer a unique platform due to their remarkable and contrasting spintronic properties, such as weak spin-orbit coupling (SOC) in graphene and strong SOC in molybdenum disulfide (MoS$_2$). Here we combine graphene and MoS$_2$ in a van der Waals heterostructure to realize the electric control of the spin polarization and spin lifetime, and demonstrated a spin field-effect transistor (spin-FET) at room temperature in a non-local measurement geometry. We observe electrical gate control of the spin valve signal due to pure spin transport and Hanle spin precession signals in the graphene channel in proximity with MoS$_2$ at room temperature. We show that this unprecedented control over the spin polarization and lifetime stems from the gate-tuning of the Schottky barrier at the MoS$_2$/graphene interface and MoS$_2$ channel conductivity leading to spin interaction with high SOC material. The all-electrical creation, transport and control of the spin polarization in a spin-FET device at room temperature is a substantial step in the field of spintronics. It opens a new platform for the interplay of spin, charge and orbital degrees of freedom for testing a plethora of exotic physical phenomena, which can be key building blocks in future device architectures.