University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Wednesday, October 1st 2014
3:35 pm:
Speaker: Chris Leighton, University of Minnesota
Subject: Complex Oxides: From Minerals, to Electronic Heterogeneity, to Oxide Electronics
Refreshments served in Room 216 Physics after colloquium

Complex oxides are simply the solids (typically crystalline) formed by bonding
multiple metal cations with oxygen. These materials have been known for many years, make up a large class of naturally occurring minerals, and have emerged over the last two decades or so as one of the most important platforms for the discovery of new phenomena in condensed matter physics. High temperature superconductivity and colossal magnetoresistance (up to a 1012 change in electrical resistivity in an applied magnetic field) provide the highest profile examples, but these materials also support ferroelectricity, multiferroicity (coexistence of two or more ferroic order parameters), oxygen conduction, etc. In this talk I will focus on just one class of complex oxides, the perovskites, named after the mineral prototype CaTiO3 . Focusing on electronic and magnetic behavior I will review the basic physics and chemistry of these materials, emphasizing in particular their instability towards nanoscale electronic heterogeneity (otherwise termed electronic or magnetic phase separation). In the final part of the colloquium I will review recent work from my group attempting to understand “dead layers” in these materials, where the desirable magnetic and electronic properties are heavily suppressed at surfaces and interfaces. The results point to controlled crystallization of oxygen defects as a new means to tune the behavior of oxide interfaces, potentially important in oxide electronic devices.

Faculty Host: Rafael Fernandes

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