korean english


Home > 게시판 > 세미나

아래와 같이 콜로퀴움을 개최하오니 많이 참석해 주시기 바랍니다.

4시 20분부터 제1과학관 31214 e+강의실에서 다과를 준비하오니 많은 참석 부탁드립니다


아 래


제목: Epitaxial Oxygen Sponge


연사: 최   우   석  교수님 (성균관대학교)


일시: 2013년 9월 11일(수) 오후4:30


장소: 제1과학관 31214  e+첨단강의실 


초록: Multivalent transition metal oxide SrCoOx (SCO) has rich oxygen content (x)–dependent electronic, magnetic and optical phases, ranging from antiferromagnetic insulator to ferromagnetic metal. The modification of x changes the valence state of Co, which governs the overall material’s property. The redox reaction of the material and the resultant changes in the physical properties are physically interesting and are essential ingredients in applications such as solid oxide fuel cells, gas sensors, and many other devices that exploits ionic (oxygen) transport property.

Using real-time x-ray diffraction and optical spectroscopy complemented by first principles calculation, we studied lattice structures, optical properties, and electronic structures of SCO epitaxial thin films. In particular, brownmillerite SrCoO2.5 (BM-SCO) and perovskite SrCoO3 (PV-SCO) thin films have been studied in detail, where they have distinct crystal structures and valence states. BM-SCO has a one-dimensional oxygen vacancy ordered structure with a common Co3+ valence state. On the contrary, PV-SCO has a typical perovskite structure. Both experimental and theoretical results agreed that these two films have drastically different electronic ground states as well. While BM-SCO showed an insulating ground state with an optical band gap of ~0.5 eV, PV-SCO showed a clear Drude response suggesting a metallic ground state. Despite such large discrepancy in the physical properties, however, we found that a topotactic transformation between two structurally distinct phases could be readily achieved. The temperature dependent, ambient controlled real-time ellipsometry conspicuously showed that these two topotactic phases could be reversibly obtained at relatively low temperatures. Our study suggests that the electronic structure of SCO can be switched reversibly through oxygen insertion and extraction, simultaneously with the crystal lattice structure and Co valence state. Thus, it provides an invaluable insight in studying the link between the fundamental physical properties and its technological applications of transition metal oxide epitaxial thin films.

번호 제목 날짜 조회 수
공지 <12/8(Thu.) 11:00am>노벨상 소개 강연 - 2016년 노벨 물리학상: 위상 응집 물리의 탄생 2016.11.28 1090387
217 <Oct. 5(Wed.) 4:30 PM> 국제원자력기구 (IAEA)와 핵데이터 2016.09.22 63968
216 <10/13(Thu.) 13:00>기술융합을 통한 의료혁명과 물리학의 역할 2016.09.29 79688
215 <Oct. 12(Wed.) 4:30 PM> Silk as a biocompatible optical material 2016.10.05 66886
214 <10/12(Wed.) 11:00am>Unconventional Superconductivity: From History to Mystery 2016.10.10 90698
213 <10/25(Tue.) 11:00am>Crystallization of Water under Modulating Pressures 2016.10.10 64211
212 <10/11(Tue.) 15:00>Analysis of Individual Terrestrial Gamma-ray Flashes 2016.10.10 74218
211 <Oct. 19(Wed.) 10:00 AM> Hyper-Kamiokande project -The future of neutrino physics in Japan 2016.10.12 64022
210 <10/25(Tue.) 11:00am>Crystallization of Water under Modulating Pressures 2016.10.14 64739
209 <Nov. 2(Wed.) 4:30 PM> 현대 우주론 이론과 관찰 (Theories and observations of modern cosmology) 2016.10.19 56129
208 <Nov. 9(Wed.) 4:30 PM> 20-nm resolution imaging of brain circuitry by next-generation expansion microscopy 2016.11.02 54741
207 <Nov. 16(Wed.) 4:30 PM> Two-dimensional Chiral Materials and Topological Insulators 2016.11.10 204652
206 <Nov. 23(Wed.) 4:30 PM> Dry (Plasma) etch process in Semiconductor Device 2016.11.16 63203
205 <Nov. 30(Wed.) 4:30 PM> Chiral solitons for topological informatics 2016.11.23 82663
204 <Dec. 7(Wed.) 4:30 PM>Mechanotransduction of cells in vitro(세포기능의 역학적 조절) 2016.11.30 85170
203 <12/2(Fri.) 14:00>Overview of HIMAC facility 2016.12.01 56322
202 <Dec. 14(Wed.) 4:30 PM>중력과 양자 얽힘 (tentative) 2016.12.07 54876
201 2017학년도 1학기 콜로퀴움 일정 2017.01.05 333747
200 <Mar. 15(Wed.) 4:30 PM>반도체 Fab Process와 물리학 전공자 2017.03.14 54731
199 <Mar. 22(Wed.) 4:30 PM>Symmetry and topology in the electronic structure of solids 2017.03.15 57281