Atomic structure and electronic properties of MgO grain boundaries in tunnelling magnetoresistive devices

Jonathan J. Bean, Mitsuhiro Saito, Shunsuke Fukami, Hideo Sato, Shoji Ikeda, Hideo Ohno, Yuichi Ikuhara, Keith P. McKenna

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Polycrystalline metal oxides find diverse applications in areas such as nanoelectronics, photovoltaics and catalysis. Although grain boundary defects are ubiquitous their structure and electronic properties are very poorly understood since it is extremely challenging to probe the structure of buried interfaces directly. In this paper we combine novel plan-view high-resolution transmission electron microscopy and first principles calculations to provide atomic level understanding of the structure and properties of grain boundaries in the barrier layer of a magnetic tunnel junction. We show that the highly [001] textured MgO films contain numerous tilt grain boundaries. First principles calculations reveal how these grain boundaries are associated with locally reduced band gaps (by up to 3 eV). Using a simple model we show how shunting a proportion of the tunnelling current through grain boundaries imposes limits on the maximum magnetoresistance that can be achieved in devices.

Original languageEnglish
Article number45594
JournalScientific reports
Volume7
DOIs
Publication statusPublished - 2017 Apr 4

ASJC Scopus subject areas

  • General

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