Coupling Magnetism to Electricity in Multiferroic Heterostructures

Abstract: Complex perovskite oxides exhibit a rich spectrum of functional responses, including magnetism, ferroelectricity, highly correlated electron behavior, superconductivity, etc.   The basic materials physics of such materials provide the ideal playground for interdisciplinary scientific exploration.  Over the past decade we have been exploring the science of such materials (for example, colossal magnetoresistance, ferroelectricity, etc) in thin film form by creating epitaxial heterostructures and nanostructures.  Among the large number of materials systems, there exists a small set of materials which exhibit multiple order parameters; these are known as multiferroics.  Using our work in the field of ferroelectric(FE) and ferromagnetic oxides as the background, we are now exploring such materials, as epitaxial thin films as well as nanostructures.  Specifically, we are studying the role of thin film growth, heteroepitaxy and processing on the basic properties as well as magnitude of the coupling between the order parameters.  In our work we are exploring the switchability of the antiferromagnetic order using this coupling. 

What is the importance of this work ?  Antiferromagnets(AFM) are pervasive in the recording industry. They are used as exchange biasing layers in MTJ’s etc.  However, to date there has been no antiferomagnet that is electrically tunable.  We believe that the multiferroic BiFeO3 is one compound where this can be observed at room temperature.  The next step is to explore the coupling of a ferromagnet to this antiferromagnet through the exchange biasing concept.  Ultimately, this will give us the opportunity to switch the magnetic state in a ferromagnet( and therefore the spin polarization direction) by simply applying an electric field to the underlying antiferromagnetic ferroelectric.  In this talk, I will describe our progress to date on this exciting possibility.  

Bio : Ramesh pursues key materials physics and technological problems in complex multifunctional oxides. Using conducting oxides, he solved the 30-year enigma of polarization fatigue in ferroelectrics. He pioneered research into manganites coining the term, Colossal Magnetoresistive (CMR) Oxides. His work on multiferroics demonstrated electric field control of ferromagnetism, a critical step towards ultralow power memory and logic elements. His extensive publications on the synthesis and materials physics of complex oxides are highly cited (over 100,000 citations, H-factor >150).  He is a fellow of APS, AAAS & MRS and an elected member of the U.S. National Academy of Engineering, a Foreign member of the Royal Society of London, the Indian National Science Academy, the Indian National Academy of Engineering  and a Fellow of the American Academy for Arts and Sciences. His awards include the Humboldt Senior Scientist Prize, the MRS Turnbull Lectureship Prize, the APS Adler Lectureship and McGroddy New Materials Prize, the TMS Bardeen Prize and the IUPAP Magnetism Prize and Neel Medal and the Europhysics Prize in 2022. He was recognized as a Thomson-Reuters Citation Laureate in Physics for his work on multiferroics. He served as the Founding Director of the successful Department of Energy SunShot Initiative in the Obama administration, envisioning and coordinating the R&D funding of the U.S. Solar Program, spearheading the reduction in the cost of Solar Energy. He also served as the Deputy Director of Oak Ridge National Laboratory and the Associate Lab Director at LBNL. Most recently, he served on the Biden-Harris Transition Team for Energy. He is also a co-founder of Kepler Computing, which is focused on low power computing using ferroelectrics. Starting 15 August, he is serving as the Executive Vice President for Research at Rice University

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.