# High quality electrostatically defined hall bars in monolayer graphene

## TL;DR

This paper presents a method to create high-quality, electrostatically defined graphene structures using the $
u=0$ insulating state at modest magnetic fields, enabling precise control without quality loss.

## Contribution

It introduces a novel approach to define graphene device geometries electrostatically via the $
u=0$ state, maintaining high quality and enabling advanced quantum transport studies.

## Key findings

- Successful creation of high-quality gate-defined graphene structures
- Preservation of fragile quantum states like fractional quantum Hall states
- Verification that device quality is maintained with multiple gates

## Abstract

Realizing graphene's promise as an atomically thin and tunable platform for fundamental studies and future applications in quantum transport requires the ability to electrostatically define the geometry of the structure and control the carrier concentration, without compromising the quality of the system. Here, we demonstrate the working principle of a new generation of high quality gate defined graphene samples, where the challenge of doing so in a gapless semiconductor is overcome by using the $\nu=0$ insulating state, which emerges at modest applied magnetic fields. In order to verify that the quality of our devices is not compromised by the presence of multiple gates we compare the electronic transport response of different sample geometries, paying close attention to fragile quantum states, such as the fractional quantum Hall (FQH) states, that are highly susceptible to disorder. The ability to define local depletion regions without compromising device quality establishes a new approach towards structuring graphene-based quantum transport devices.