Spin-orbit interaction in Pt or Bi2Te3 nanoparticle-decorated graphene realized by a nanoneedle method

TL;DR

This study demonstrates a novel nanoneedle method to decorate graphene with heavy nanoparticles, inducing significant spin-orbit interactions and revealing potential for topological phases and spintronic applications.

Contribution

It introduces an original nanoneedle technique for low-damage decoration of graphene with Pt or Bi2Te3 nanoparticles, enabling control of spin-orbit interactions.

Findings

Observation of particle-density-dependent non-local resistance peaks

Detection of large spin Hall effect energies (~30 meV)

Evidence of Bi-C and Te-C coupling orbitals

Abstract

The introduction of spin-orbit interactions (SOIs) and the subsequent appearance of a two-dimensional (2D) topological phase are crucial for voltage-controlled and zero-emission energy spintronic devices. In contrast, graphene basically lacks SOIs due to the small mass of the carbon atom, and appropriate experimental reports for SOIs are rare. Here, we control small-amount (cover ratios < 8%) random decoration of heavy nanoparticles [platinum (Pt) or bismuth telluride (Bi2Te3)] onto mono-layer graphene by developing an original nanoneedle method. X-ray photoelectron spectra support low-damage and low-contamination decoration of the nanoparticles, suggesting the presence of Bi-C and Te-C coupling orbitals. In the samples, we find particle-density-dependent non-local resistance (RNL) peaks, which are attributed to the (inverse) spin Hall effect (SHE) arising from SOI with energies as large as about 30 meV. This is a larger value than in previous reports and supported by scanning tunneling spectroscopy. The present observation should lead to topological phases of graphene, which can be introduced by random decoration with controlled small amounts of heavy nanoparticles, and their applications.