Unraveling hausmannite (Mn3O4) thin films surface structure by X ray linear dichroism

Abstract

There is an urgent need to understand the relationship between oxide thin-film surface plane and its electronic properties because of its key role in molecular adsorption and surface reactivity as requested in optimal applications of magnetism to catalysis. The present work intends to resolve this open issue by investigating the surface structure and electronic properties of Mn3O4 thin films. To this end, well-defined Mn3O4 (110) and (001) surfaces were prepared and their electronic properties were explored by X-ray linear dichroism, XLD (the search light effect). The Mn3O4 thin films were extensively prepared on distinct noble metal substrates (Au(111), Cu (111), Ag (001)) with the aim of disentangling the film’s electronic structure and their corresponding film strain from their free surface, bulk, and interface contribution. Our experiments revealed the sensitivity of the 3d orbital occupancy and their intensity ratio (dx2−y2/d3z2−r2) to the surface orientation. The variation of relative 3d occupation as a function of strain was quantified by using the XLD sum rules. These results reveal important aspects for the identification and further engineering of well-defined crystallographic surfaces in several fields of applications.