量子物質科學協同創新中心seminar：Coupling Magnetism To Electricity In Multiferroic Heterostructures

報告題目： Coupling Magnetism To Electricity In Multiferroic Heterostructures 報告人： R. Ramesh Department of Materials Science and Engineering and Department of Physics, and Lawrence Berkeley National Laboratory, University of California, Berkeley 報告時間： 2015-5-12 16:00 報告地點：理科樓鄭裕彤大講堂摘要： 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. 個人簡介： Ramesh graduated from U.C. Berkeley with a Ph.D. in Materials Science in 1987. He returned to Berkeley in 2004, and was the Plato Malozemoff Chair in Materials Science and Physics 2009-2012. From 1989-1995, Ramesh worked for Bellcore (Bell Communications Research) where he initiated research in several key areas of oxide electronics, including ferroelectric nonvolatile memories. In 1994, in collaboration with S. Jin (Lucent Technologies), he initiated research into manganite thin films and helped coin the term, Colossal Magnetoresistive (CMR) Oxides. His current research interests include multiferroics, thermoelectric and photovoltaic energy conversion in complex oxide heterostructures.
Ramesh has published extensively on the synthesis and materials physics of complex oxide materials and received the Humboldt Senior Scientist Prize and Fellowship to the American Physical Society (2001). In 2005, he was elected a Fellow of the American Association for the Advancement of Science as well as the David Adler Lectureship of the American Physical Society. In 2007, he was awarded the Materials Research Society David Turnbull Lectureship Award and, in 2009, was elected Fellow of MRS and is the recipient of the 2010 APS McGroddy New Materials Prize. In addition, he was elected as a member of the National Academy of Engineering in 2011. In 2011 he served as Director of the SunShot Initiative through the U.S. Department of Energy. In June of 2013, Ramesh joined Oak Ridge National Laboratory as Deputy Lab Director for Science and Technology. In Auguest of 2014, Ramesh returned to Berkeley and named as Berkeley Lab's associate Laboratory Director for Energy Technologies.