# Structure of Superconducting Ca-intercalated Bilayer Graphene/SiC studied using Total-Reflection High-Energy Positron Diffraction

## TL;DR

This study reveals the atomic structure of superconducting Ca-intercalated bilayer graphene on SiC using positron diffraction, showing Ca atoms intercalate between the buffer layer and graphene, and correlates this with a superconducting transition at 4K.

## Contribution

First to identify the atomic arrangement of Ca in intercalated bilayer graphene and its relation to superconductivity using total-reflection high-energy positron diffraction.

## Key findings

- Ca atoms intercalate in the graphene-buffer interlayer
- Superconducting transition observed at 4K
- Atomic structure correlates with superconductivity

## Abstract

We have investigated the atomic structure of superconducting Ca-intercalated bilayer graphene on a SiC(0001) substrate using total-reflection high-energy positron diffraction. By comparing the experimental rocking-curves with ones calculated for various structural models using a full-dynamical theory, we have found that Ca atoms are intercalated in the graphene-buffer interlayer, rather than between the two graphene layers. From transport measurements, the superconducting transition was observed to be at Tc_onset = 4K for this structure. This study is the first to clearly identify the relation between the atomic arrangement and superconductivity in Ca-intercalated bilayer graphene.

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Source: https://tomesphere.com/paper/1906.11535