Ramamoorthy Ramesh, Lawrence Berkeley National Laboratory, University of California, Berkeley
Electric Field Control of Magnetism
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 with an eye toward real applications. Over the past decade the oxide community has been exploring the science of such materials as crystals and in thin-film form by creating epitaxial heterostructures and nanostructures. Among the large number of materials systems, there exists a small set of materials that exhibit multiple order parameters; these are known as multiferroics, particularly, the coexistence of ferroelectricity and some form of ordered magnetism (typically antiferromagnetism). The scientcommunity has been able to demonstrate electric field control of both antiferromagnetism and ferromagnetism at room temperature. Current work is focused on ultralow energy (1 attoJoule/operation) electric field manipulation of magnetism as the backbone for the next generation of ultralow power electronics. In this lecture, I will describe our progress to date on this exciting possibility. The lecture will conclude with a summary of where the future research is going.
About Ramamoorthy Ramesh
Ramamoorthy Ramesh graduated from the University of California, Berkeley, in 1987. He returned to Berkeley in 2004 and is currently the Purnendu Chatterjee Chair Professor in Materials Science and Physics. From 1989 to 1995, at Bellcore, he initiated research in several key areas of oxide electronics, including ferroelectric nonvolatile memories. His landmark contributions in ferroelectrics came through the recognition that conducting oxide electrodes are the solution to the problem of polarization fatigue, which for 30 years, remained an enigma and unsolved problem. In 1994, in collaboration with S. Jin (Lucent Technologies), he initiated research into manganite thin films and they coined the term Colossal Magnetoresistive (CMR) Oxides. He initiated pioneering research into multiferroic oxides at the University of Maryland.
At Berkeley, Ramesh continues to pursue key scientific and technological problems in complex multifunctional oxide thin films, nanostructures and heterostructures. His group demonstrated the existence of a large ferroelectric polarization in multiferroic BiFeO3 films, in agreement with first-principle predictions; they also demonstrated electric field control of antiferromagnetism as well as ferromagnetism, a critical step toward the next generation of ultralow power storage and spintronics devices that are completely electric field controlled.
He has published extensively on the synthesis and materials physics of complex oxide materials and his work is highly cited (over 65,000 citations, H-factor =110). He is a Fellow of the American Physical Society (APS), the American Association for the Advancement of Science (AAAS) and the Materials Research Society (MRS). Ramesh has been recognized with a Humboldt Senior Scientist Prize, the American Physical Society David Adler Lectureship and the James McGroddy Prize and the TMS Bardeen Prize. In 2014, he was recognized as a Thomson-Reuters Citation Laureate in Physics for his work on multiferroics.
From December 2010 to August 2012, he served as the Founding Director of the SunShot Initiative at the U.S. Department of Energy, overseeing and coordinating the R&D activities and funding (300M$/year) of the U.S. Solar Program. In 2011, he was elected to the National Academy of Engineering. He is currently the Associate Laboratory Director for Energy Technologies at the Lawrence Berkeley National Laboratory.