Graphene as an Ideal Buffer Layer for the Growth of High-Quality Ultrathin Cr₂O₃Layers on Ni(111)

Abstract

Metal−oxide nanostructures play a fundamental role in a large number of technological applications, ranging from chemical sensors to data storage devices. As the size of the devices shrinks down to the nanoscale, it is mandatory to obtain sharp and good quality interfaces. Here, it is shown that a two-dimensional material, namely, graphene, can be exploited as an ideal buffer layer to tailor the properties of the interface between a metallic substrate and an ultrathin oxide. This is proven at the interface between an ultrathin film of the magnetoelectric antiferromagnetic oxide Cr 2 O 3 and a Ni(111) single crystal substrate. The chemical composition of the samples has been studied by means of X-ray photoemission spectroscopy, showing that the insertion of graphene, which remains buried at the interface, is able to prevent the oxidation of the substrate. This protective action leads to an ordered and layer-by-layer growth, as revealed by scanning tunneling microscopy data. The structural analysis performed by lowenergy electron diffraction indicates that the oxide layer grown on graphene experiences a significant compressive strain, which strongly influences the surface electronic structure observed by scanning tunneling spectroscopy.

Bandgap engineering of two-dimensional semiconductor materials

“…Large-bandgap materials such as hexagonal boron nitride (h-BN) 27 play a critical role in 2D materials, as its inert and ultraflat nature allows it to serve as a substrate for high-mobility 2D devices. Other large-bandgap materials include the transitionmetal oxides (TMO) such as the 2H phase MoO 2 , 1T phase MnO 2 , and, more recently, the octahedral α-MoO 3 , which exhibit hyperbolic optical behavior 28 , the chromium oxide (e.g., Cr 2 O 3 ), known for its multiferroic properties 29 , and mica 30 .…”

“…npj 2D Materials and Applications (2020)29 Published in partnership with FCT NOVA with the support of E-MRS…”

Magnetic response and electronic states of well defined Graphene/Fe/Ir(111) heterostructure

“…It has been shown that a tiny magnetic moment arises on the carbon atoms, induced by the strong hybridization of graphene π orbitals with Ni or Co 3d states [3,8,11,12]. Furthermore, graphene grown on metals protects highly reactive magnetic surfaces and stabilizes them against oxidation [13][14][15]. Whereas recently a large research effort has been dedicated to investigate Gr-Ni and Gr-Co heterostructures, only a few experimental results for graphene grown on Fe surfaces are available [16][17][18], though iron is the most widespread transition metal, and the technology of passivated Fe films with a graphene membrane can be appealing for several reasons.…”

Study on Local Residual Stress in a Nanocrystalline Cr2O3 Coating by Micro-Raman Spectroscopy

“…Chromium trioxide (Cr 2 O 3 ), also known as chromium oxide, is used as a functional coating in many fields for its excellent properties such as high hardness, wear resistance, corrosion resistance and low coefficient of friction [1][2][3][4]. Cr 2 O 3 coatings are usually prepared by gas phase deposition.…”