KOSEN 한인과학기술자네트워크

We are primarily interested in synthesis and characterization of functional transition metal oxide thin films, especially as applied to multiferroic phenomena,magnetoelectric devices, and energy-related applications. Oxides, the most abundant materials, would exhibit novel electronic properties as like metal-insulator transitions, colossal magnetoresistance, and high Tc superconductivity. These phenomena could hardly be understood only by conventional band structure concept because of strong electron correlations. The rapid progress in this area during the last twenty years enables us to design and synthesize theses materials. Although it is still at the very early stages as compared with conventional semiconductors and intermetallic compounds, we now know a lot more about the basic rules. Our research is focused on exploring pathways to control magnetism and strongly correlated phenomena with an electric field based on oxide thin films using the following approaches : Growth and Characterization of Transition Metal Oxide Thin films : Laser molecular beam epitaxy (Laser-MBE) and pulsed laser deposition (PLD) techniques would be used for high-crystalline epitaxial film growths with atomic precision; Control of strain, synthesis of artificial structures (ordered structures, superlattices, multilayers), and stabilization of metastable phases through heteroepitaxy; Materials Processing for Devices and Nanoscale Characterization : Device fabrications using photo-lithography and dry-etching techniques; Understanding materials properties at the nanoscale using scanning probes, piezoresponse force microcopy, conducting-AFM; Understanding and Modulation of Strongly Correlated Phenomena in Thin Films : Inter-coupled phenomena of lattice, spin, and orbital degrees of freedom Metal-insulator transition, colossal magnetoresistance, orbital/charge ordering, frustrated magnets, dilute magnetic semiconductors; Transport measurements of strongly correlated electrons at low temperatures and high magnetic field, and electric modulation of the phenomena; Low dimensional high-mobility conduction and new magnetism in functional oxide interfaces; New Functionality in Thin films : Multiferroic thin films for magnetoelectric devices and spintronic applications; Solar energy conversion to electric power through ferroelectric heterostructures and artificial superlattices; Non-volatile information storage, ferroelectric memories, resistance-switching memories; Electric field control of electronic conduction, ferroelectricity, and magnetism; Field effect devices; Use of Large Facilities : Resonant X-ray scattering for probing orbital/charge ordered systems using synchrotron source; Nanoscale characterization of defect/electronic structure through state-of-the-art characterization tools of photoemission electron microscopy (PEEM) and electron microscopy to carry out element specific spectromicroscopy.