Transport Spectroscopy of Sublattice-Resolved Resonant Scattering in Hydrogen-Doped Bilayer Graphene

TL;DR

This study demonstrates sublattice-specific hydrogen adsorption in bilayer graphene using transport measurements, revealing distinct resonant scattering peaks and enabling controlled doping for potential magnetic applications.

Contribution

The paper introduces a transport-based method to distinguish and control hydrogen adsorption on different sublattices of bilayer graphene, advancing sublattice-specific doping techniques.

Findings

Two distinct resonant scattering peaks linked to different sublattices.

Hydrogen prefers adsorption on the {eta}-sublattice.

Selective desorption enables sublattice-specific doping.

Abstract

We report the experimental observation of sublattice-resolved resonant scattering in bilayer graphene by performing simultaneous cryogenic atomic hydrogen doping and electron transport measurements in ultrahigh vacuum. This allows us to monitor the hydrogen adsorption on the different sublattices of bilayer graphene without atomic-scale microscopy. Specifically, we detect two distinct resonant scattering peaks in the gate-dependent resistance, which evolve as a function of atomic hydrogen dosage. Theoretical calculations show that one of the peaks originates from resonant scattering by hydrogen adatoms on the {\alpha}-sublattice (dimer site) while the other originates from hydrogen adatoms on the \b{eta}-sublattice (non-dimer site), thereby enabling a method for characterizing the relative sublattice occupancy via transport measurements. Utilizing this new capability, we investigate the adsorption and thermal desorption of hydrogen adatoms via controlled annealing and conclude that hydrogen adsorption on the \b{eta}-sublattice is energetically favored. Through site-selective desorption from the {\alpha}-sublattice, we realize hydrogen doping with adatoms primarily on a single sublattice, which is highly desired for generating ferromagnetism.