PHYSICS/BK21 SEMINAR[10.01.20]
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| Real-Space Imaging of Strain-Induced Electronic Phase Separation near the Mott Metal-Insulator Transition * Speaker : Dr. Tae-Hwan Kim (Center for Nanophase Materials Sciences, Oak Ridge National Laboratory) * Place : Physics Seminar Room (Science Bldg, 3-201) * Date & Time : Jan, 20 (Wed) 4:00 ~ 5:00 pm * Abstract Transition-metal oxides with multiple nearly degenerate states show very complicated phase diagrams. Small perturbations can often dramatically change their functionalities. It is believed that electronic phase separations (PS) play an important role in the exotic functionality. Direct experimental observation of PS has thus become crucial to understanding underlying mechanisms of the striking functionalities, as demonstrated in the breakthrough in understating CMR after revealing PS in manganites. We have observed the PS and the evolutions of phase domains with temperature near the Mott transition in a Mn-doped bilayered ruthenate. Our experimental approach combines electron microscopy, scanning tunneling microscopy, and electron transport spectroscopy, which provide unprecedented capabilities of imaging PS and interrogating individual microscopic domains in situ. By imaging phase domains with electron microscopy and interrogating individual domains via electron transport spectroscopy, we show in real-space that the microscopic phase competition and the Mott-type metal-insulator transition are extremely sensitive to applied mechanical stress. Strikingly, the coexistence of competing phases is not associated with inhomogeneous doping. The revealed dynamic phase evolution with applied stress provides the first direct evidence for the important role of strain effect in both phase separation and Mott metal-insulator transition due to strong electron-lattice coupling in correlated systems. Contact Person : Prof. Yoon Hee Jeong (054-279-2078, yhj@postech.ac.kr) |
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