Physics Colloquium- John Mitchell (Argonne Nat’l Laboratory) 10/19
October 19, 2022
3:00 PM - 4:00 PM
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Title: “A Nickel for Your Thoughts”
Abstract: The 2019 announcement of superconductivity by Harold Hwang in thin films of ‘infinite layer’ Nd1-xSrxNiO2 and this year by Julia Mundy in quintuple layer Nd6Ni5O12 has at last justified a more than 30 year search begun soon after the discovery of high-Tc cuprates. At the same time, it has re-emphasized the importance of exploring nickel-based oxide systems both as superconductor models and in their own right. In this talk, I will summarize the current state of nickelate superconductors and then present our recent efforts studying two kinds of (nonsuperconducting) trilayer nickelate model systems: (1) R4Ni3O8, where we have been interested in exploring how correlated metals evolve into charge- and spin-stripe ordered insulators and (2) R4Ni3O10 where we have discovered intertwined charge and spin density waves coexisting with an unexpected (and perhaps unprecedented) type of ‘bootstrapped’ 2D- to 3D magnetic crossover. As background, I will discuss how high pressure crystal growth made this work possible and suggest a few possible future directions where high pressure measurements could be enlightening.
John F. Mitchell is an Argonne Distinguished Fellow and Deputy Director of the Materials Science Division. He received his A.B. in Chemistry from Cornell University in 1987 and his Ph.D. from the University of Chicago in 1993 for theoretical studies of defect structures and order-disorder transitions of early transition metal chalcogenides. Appointed to Argonne staff in 1996, his current research emphasizes strategic synthesis, crystal growth, and structural studies of correlated electron transition metal systems, quantum magnets and topological materials. Mitchell was awarded the DOE Early Career Award and the Presidential Early Career Award for Scientists and Engineers in 1999 and 2000, respectively. He received the University of Chicago Distinguished Performance Award for Argonne Scientists in 2006. He is a Fellow of the American Physical Society, and a member of the Materials Research Society, American Association for the Advancement of Science, Materials Research Society, and American Chemical Society and has served on the Chair Line of the APS Division of Materials Physics.
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