Modification of electronic structure and morphology of Ni2MnGa(100) by Cr adlayers

TL;DR

This study investigates how Cr adlayers modify the electronic structure and magnetic properties of Ni2MnGa(100), revealing ferromagnetic and antiferromagnetic phases depending on layer thickness through microscopy, spectroscopy, and theoretical calculations.

Contribution

It demonstrates the epitaxial growth, magnetic phase transition, and electronic structure changes of Cr adlayers on Ni2MnGa(100) using combined experimental and theoretical methods.

Findings

Cr forms epitaxial islands up to 4 atomic layers.

Thin Cr layer is ferromagnetic as shown by DFT and spectroscopy.

Thick Cr layer becomes antiferromagnetic.

Abstract

The growth of Cr adlayers on the Mn-Ga terminated surface of Ni2MnGa(100) has been studied in this work. We show formation of islands of epitaxial Cr layer up to 4 atomic layer heights using scanning tunneling microscopy, while core-level x-ray photoelectron spectroscopy (XPS) indicates absence of any intermixing of the adlayer and the substrate. The density of states (DOS) of the thin Cr layer (2.7 ML) measured by scanning tunneling spectroscopy exhibits nice agreement with density functional theory (DFT) that establishes that it is ferromagnetic. In contrast, a thick layer of Cr that also grows epitaxially on Ni2MnGa(100) is shown to be antiferromagnetic by comparing its XPS valence band with the DOS for bulk Cr calculated by DFT.