Hysteresis loops of the magnetoconductance in graphene devices

TL;DR

This study investigates the hysteresis in magnetoconductance of graphene devices at low temperatures, revealing that paramagnetic centers influence conductance fluctuations and exhibit magnetization reversal behavior.

Contribution

It provides new insights into the hysteresis phenomena in graphene's magnetoconductance linked to paramagnetic defect centers.

Findings

Hysteresis loops are observed in magnetoconductance at various device sizes.

The hysteresis depends on gate voltage and transport regime.

Magnetization reversal of paramagnetic centers causes the observed hysteresis.

Abstract

We report very low temperature magnetoconductance DeltaG measurements on graphene devices with the magnetic field H applied parallel to the carbon sheet. The DeltaG(H) signal depends on the gate voltage Vg and its sign is related with the universal conductance fluctuations. When the magnetic field is swept at fast rates, DeltaG displays hysteresis loops evident for different sizes and at different transport regimes of the devices. We attribute this to the magnetization reversal of paramagnetic centres in graphene layer, which might originate from defects in our devices.