Spin-dependent photovoltage in graphene/MoS2-based field-effect transistors

TL;DR

This study demonstrates spin-dependent photovoltage signals in graphene/MoS2 transistors at Gigahertz frequencies, revealing insights into spin-related phenomena and their independence from gate bias, with implications for 2D quantum material sensors.

Contribution

It reports the first observation of gate-bias independent spin resonance photovoltage in graphene/MoS2 transistors at Gigahertz frequencies, highlighting spin-dependent effects in 2D heterostructures.

Findings

Magnetic resonance photovoltage detected in the GHz range.

Spin-related signals are independent of gate bias.

Photovoltage drops are linked to spin polarization decreases.

Abstract

It has recently been shown that Terahertz sensors can effectively detect the spin resonances of Dirac fermions in graphene. The associated photovoltaic measurement technique allows for the investigation of the intrinsic spin-orbit coupling in graphene as well as its topological properties from microwave to Terahertz frequencies. In this work, using graphene/MoS2-based Field-Effect Transistors, we observed a magnetic resonance photovoltage signal in the Gigahertz range that is independent of the gate bias. The dispersion of the associated spin-flip transitions remains intriguingly unaffected by the MoS2 layer. In parallel, the spin-related signal consistently appears as a drop in photovoltage, regardless of the signal's polarity or origin, whether it arises from plasma wave rectification or thermoelectric effects. This behavior is interpreted as a decrease in the system's spin polarization due to spin-dependent recombination or scattering of photocarriers. Understanding the various photovoltaic signals in highly sensitive Gigahertz/Terahertz sensors paves the way for exploring spin-dependent mechanisms in two-dimensional quantum materials, influenced by proximity effects such as spin-orbit coupling, topology, and magnetism.