Atomic and Electronic Structure of the BaTiO3/Fe Interface in Multiferroic Tunnel Junctions

• Published in: Nano letters Vol. 12; no. 1; pp. 376 - 382
• Main Authors: Bocher, Laura, Gloter, Alexandre, Crassous, Arnaud, Garcia, Vincent, March, Katia, Zobelli, Alberto, Valencia, Sergio, Enouz-Vedrenne, Shaïma, Moya, Xavier, Marthur, Neil D, Deranlot, Cyrile, Fusil, Stéphane, Bouzehouane, Karim, Bibes, Manuel, Barthélémy, Agnès, Colliex, Christian, Stéphan, Odile
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 11.01.2012
• Subjects: Barium Compounds - chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electric Conductivity; Electron Transport; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; Iron - chemistry; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Macromolecular Substances - chemistry; Magnetic properties and materials; Magnetic properties of nanostructures; Materials Testing; Molecular Conformation; Nanostructures - chemistry; Nanostructures - ultrastructure; Particle Size; Physics; Semiconductors; Surface Properties; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Titanium - chemistry; Atomically resolved EELS; ab initio calculations; aberration-corrected STEM; multiferroic nanojunctions; Electronic properties; Image resolution; Iron oxide; Tunnel effect; Theoretical study; Ferromagnetic materials; Iron; Barium titanates; Nanostructures; Interfaces; Nanometer scale; Electronic structure; EEL spectroscopy; Ferroelectric materials; Atomistic model; Aberrations; Density functional method; Tunnel junction; Magnetoresistance; Scanning transmission electron microscopy; Atomic structure; Magnetic properties
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/nl203657c

Artificial multiferroic tunnel junctions combining a ferroelectric tunnel barrier of BaTiO3 with magnetic electrodes display a tunnel magnetoresistance whose intensity can be controlled by the ferroelectric polarization of the barrier. This effect, called tunnel electromagnetoresistance (TEMR), and the corollary magnetoelectric coupling mechanisms at the BaTiO3/Fe interface were recently reported through macroscopic techniques. Here, we use advanced spectromicroscopy techniques by means of aberration-corrected scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) to probe locally the nanoscale structural and electronic modifications at the ferroelectric/ferromagnetic interface. Atomically resolved real-space spectroscopic techniques reveal the presence of a single FeO layer between BaTiO3 and Fe. Based on this accurate description of the studied interface, we propose an atomistic model of the ferroelectric/ferromagnetic interface further validated by comparing experimental and simulated STEM images with atomic resolution. Density functional theory calculations allow us to interpret the electronic and magnetic properties of these interfaces and to understand better their key role in the physics of multiferroics nanostructures.