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4시 10분부터 제1과학관 31214 e+강의실 앞에서 다과를 준비하오니 많은 참석 부탁드립니다

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제목: Understanding the Nature of Metal-Insulator Transition in a Single Crystalline VO2 nanowires

연사: 강   대   준 교수 (성균관대학교 물리학과)

일시: 2011년 3월 9(수) 오후4:30 장소: e+첨단강의실 (31214호실)

초록: Vanadium dioxide is a prominent example for a material exhibiting a
metal-insulator transition as a function of temperature: it undergoes
a first-order structural transition from a high-temperature metallic
phase to a low-temperature insulating phase at almost room-temperature
(T=340 K). The resistivity jumps by several orders of magnitude
through this transition, and the crystal structure changes from rutile
at high-temperature to monoclinic (so-called M1-phase) at
low-temperature. The latter is characterized by a dimerization of the
vanadium atoms into pairs, as well as a tilting of these pairs with
respect to the c-axis. Understanding the thermodynamics and structural
transformation during the Metal-Insulator Transition (MIT) is crucial
to  the underlying physical origin of phase transition in the vanadium
dioxide (VO2). Here, through the temperature-dependent in-situ high
resolution-transmission electron microscopy (HR-TEM), synchrotron XRD
and systematic electrical transport study, we have shown that the MIT
transition of VO2 nanowires is strongly affected by interplay between
strain and domain nucleation. Surprsingly, we have also observed that
the VO2 metallic phase could occur in a strain-induced metastable
monoclinic (M2) phase. These insights open the door toward more
systematic approaches to synthesis of VO2 nanostructures in desired
phase and to use for applications including ultrafast optical
switching, smart window, metamaterial, resistance RAM and synapse. I
will attempt to give you an overview of our research activity over
last 5 years on VO2 nanostructures and discuss fascinating features
and ample physics to explore.