Materials Science and Engineering Colloquium – 76206

Materials Science and Engineering Colloquium

Carolina Adamo, Stanford University – “Engineering thin films and heterostructures by molecular beam epitaxy”

“Engineering thin films and heterostructures by molecular beam epitaxy”Carolina AdamoDepartment of Applied Physics, Geballe Laboratory for Advanced Materials, Stanford University, CaliforniaFunctional oxides that exhibit exciting and potentially useful properties including superconductivity, ferroelectricity, piezoelectricity, and magnetism are being intensively studied. These properties, together with the possibility of tuning them through strain, chemical doping or the application of external fields, make such functional oxides suitable for use in microelectromechanical systems (MEMS), transistors, and field effect devices. Moreover interfaces and superlattices of correlated oxides present new opportunities for controlling and optimizing the magnetic and electric properties. Significant progress in the growth of atomic-scale multilayers opens exciting opportunities in the design of materials with novel properties. Recent examples include the new two-dimensional metallic state at the interface between a band insulator as SrTiO3 and a Mott insulator like LaTiO3 (1-3) and the emergence of improper ferroelectricity in PbTiO3/SrTiO3 superlattices (4).In this talk I will present how to engineering thin films and superlattices with abrupt and coherent interfaces by a reactive molecular-beam epitaxy. For example, we synthesize and investigate the electronic structure of oxide superlattices of the Mott insulator LaMnO3 and the band insulator SrMnO3. By controlling the separation between the LaMnO3-SrMnO3 interfaces, we have observed that the quasiparticle interactions are enhanced, driving the electronic states from a ferromagnetic polaronic metal to a pseudogapped insulating ground state. I will also introduce the nature of the ferromagnetism and the large mass enhancement observed in SrRuO3 compounds and some progress to look for room-temperature superconductors.1.A. Ohtomo, D. A. Muller, J. L. Grazul, and H. Y. Hwang, Nature 419, 378 (2002).2. S. Okamoto and A. J. Millis, Nature 428, 630 (2004).3. S. S. A. Seo, W. S. Choi, H. N. Lee, L. Yu, K. W. Kim, C. Bernhard, and T.W.Noh, Phys. Rev. Lett. 99, 266801 (2007).4.E. Bousquet, M. Dawber, N. Stucki, C. Lichtensteiger, P. Hermet, S. Gariglio, J.-M. Triscone, and P. Ghosez, Nature 452, 732 (2008).BiographyDr. Carolina Adamo is a research scientist at Stanford in the department of Applied Physics. She was a postdoctoral research associate in the Materials Science and Engineering department at Cornell University. She holds a PhD in Physics from the University of Salerno, Italy. During her doctoral studies she joined, as a visiting scholar, the Materials Science and Engineering department at the Pennsylvania State University. Her research focused on the growth of Manganite films and superlattices by Molecular-Beam Epitaxy (MBE). Current research activities include growth and control of complex electronic materials and systems where strong quantum interactions can result in unexpected and novel phenomena, including superconductivity, high thermopower, unconventional magnetism and metal-insulator transitions.
Host: Irving Herman

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