Valley Seebeck effect in gate tunable zigzag graphene nanoribbons

TL;DR

This paper introduces a valley Seebeck effect in gate-tunable zigzag graphene nanoribbons, demonstrating pure valley currents driven by thermal gradients and proposing a valley FET for potential valleytronics applications.

Contribution

It is the first to propose and analyze the valley Seebeck effect in zigzag graphene nanoribbons, linking thermal gradients with valleytronics and designing a valley FET device.

Findings

Pure valley current depends linearly on temperature gradient.

Valley FET can be controlled by gate voltage and temperature gradient.

Valley transconductance reaches up to 30 μS.

Abstract

We propose, for the first time, a valley Seebeck effect in gate tunable zigzag graphene nanoribbons as a result of the interplay between thermal gradient and valleytronics. A pure valley current is further generated by the thermal gradient as well as the external bias. In a broad temperature range, the pure valley current is found to be linearly dependent on the temperature gradient while it increases with the increasing temperature of one lead for a fixed thermal gradient. A valley field effect transistor (FET) driven by the temperature gradient is proposed that can turn on and off the pure valley current by gate voltage. The threshold gate voltage and on valley current are proportional to the temperature gradient. When the system switches on at positive gate voltage, the pure valley current is nearly independent of gate voltage. The valley transconductance is up to 30 {\mu}S if we take Ampere as the unit of the valley current. This valley FET may find potential application in future valleytronics and valley caloritronics.