# Lithographically Controlled Liquid Metal Diffusion in Graphene: Fabrication and Magnetotransport Signatures of Superconductivity

## TL;DR

A new method for creating superconducting graphene devices is developed, enabling precise control and revealing superconductivity at low temperatures.

## Contribution

A scalable lithography-guided intercalation method for fabricating superconducting graphene devices is introduced.

## Key findings

- Superconductivity with a critical temperature of approximately 3.5 K is observed in intercalated graphene devices.
- Magnetotransport measurements show transverse resistance with symmetric and antisymmetric field components.

## Abstract

Metal intercalation in epitaxial graphene enables the emergence of proximity‐induced superconductivity and modified quantum transport properties. However, systematic transport studies of intercalated graphene have been hindered by challenges in device fabrication, including processing‐induced deintercalation and instability under standard lithographic techniques. Here, a lithographically controlled intercalation approach is introduced that enables the scalable fabrication of gallium‐intercalated quasi‐freestanding bilayer graphene (QFBLG) Hall bar devices. By integrating lithographic structuring with subsequent intercalation through dedicated intercalation channels, this method ensures precise control over metal incorporation while preserving device integrity. Magnetotransport measurements reveal superconductivity with a critical temperature Tconset≈ 3.5 K and the occurrence of a transverse resistance, including both symmetric and antisymmetric field components, which is attributed to the symmetric‐in‐field component of non‐uniform currents. These results establish an advanced fabrication method for intercalated graphene devices, providing access to systematic investigations of confined 2D superconductivity and emergent electronic phases in van der Waals heterostructures.

Lithography‐guided intercalation creates a proximitized 2D superconducting Ga layer under graphene Hall bars via liquid‐metal intercalation. The image shows a Hall bar where Ga atoms from the liquid phase enter through patterned intercalation channels beneath quasi‐freestanding bilayer graphene, forming a confined 2D metal that demonstrates superconductivity near 3.5 K and suppresses the quantum Hall effect in the intercalated graphene.