Direct evidence for an interdiffused intermediate layer in bi-magnetic core-shell nanoparticles

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.-- et al.Core–shell nanoparticles attract continuously growing interest due to their numerous applications, which are driven by the possibility of tuning their functionalities by adjusting structural and morphological parameters. However, despite the critical role interdiffused interfaces may have in the properties, these are usually only estimated in indirect ways. Here we directly evidence the existence of a 1.1 nm thick (Fe,Mn)3O4 interdiffused intermediate shell in nominally γ-Fe2O3–Mn3O4 core–shell nanoparticles using resonant inelastic X-ray scattering spectroscopy combined with magnetic circular dichroism (RIXS-MCD). This recently developed magneto-spectroscopic probe exploits the unique advantages of hard X-rays (i.e., chemical selectivity, bulk sensitivity, and low self-absorption at the K pre-edge) and can be advantageously combined with transmission electron microscopy and electron energy loss spectroscopy to quantitatively elucidate the buried internal structure of complex objects. The detailed information on the structure of the nanoparticles allows understanding the influence of the interface quality on the magnetic properties.This work has been supported by the 2014-SGR-1015 and 2009-SGR-35 projects of the Generalitat de Catalunya, by the MAT2010-20616-C02 and MAT2010-16407 projects of the Ministerio de Economía y Competitividad (MINECO). MS acknowledges support from the Polish Ministry of Science and Higher Education. ME acknowledges the Spanish Ministry of Science and Innovation through the Juan de la Cierva Program. MDB acknowledges partial financial support from an ICREA-Academia Award.Peer Reviewe