Chiral charge pumping in graphene deposited on a magnetic insulator

TL;DR

This paper reports room-temperature chiral charge pumping in graphene/YIG bilayers, where dynamic magnetic excitations induce a voltage that depends on magnetization orientation, revealing broken symmetry and frequency-dependent effects.

Contribution

It demonstrates a novel chiral charge pumping effect in graphene/YIG systems at room temperature, linked to magnetic excitations and symmetry breaking.

Findings

Voltage sign reverses with magnetization orientation

Effect depends non-monotonically on spin-wave frequency

Chiral charge pumping observed at room temperature

Abstract

We demonstrate that a sizable chiral charge pumping can be achieved at room temperature in graphene/Yttrium Iron Garnet (YIG) bilayer systems. The effect, which cannot be attributed to the ordinary spin pumping, reveals itself in the creation of a dc electric field/voltage in graphene as a response to the dynamic magnetic excitations (spin waves) in an adjacent out-of-plane magnetized YIG film. We show that the induced voltage changes its sign when the orientation of the static magnetization is reversed, clearly indicating the broken spatial inversion symmetry in the studied system. The strength of effect shows a non-monotonous dependence on the spin-wave frequency, in agreement with the proposed theoretical model.