logo

korean english

게시판

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 1079608
187 <March.18(Fri) 11:00> High Pressure Synthesis and Characterization of Non-Oxide Superconductors 2016.03.14 69218
186 <8/14(Wed.)>3D-strain induced superconductivity in La2CuO4+δ using a simple vertically aligned nanocomposite approach 2019.08.13 69192
185 <5/22> Vortex partition function and 3d dualities 2012.05.21 69129
184 <9/7(금)> Kondo Effect in Chiral Orbital Bands 2012.08.31 69097
183 <6/9(화)> 세미나 개최 안내 2015.06.09 69038
182 <9/17(수)> Reshaping Micro/Nanophotonics by Programmable Soft-Matter 2014.09.15 69014
181 <Dec.30(Wed) 16:30> Some basics about the thermoelectricity; the semi-classical Boltzmann transport approach 2015.12.24 68990
180 <12/10(수)> Magnetic Resonance Imaging: What is relevant to physics 2014.12.04 68819
179 <Oct.2(Wed.)> Fundamental physics with high-energy atmospheric and cosmic neutrinos today and in the future 2019.09.26 68581
178 <May. 11(Wed.) 4:30 PM> In-situ x-ray studies of functional oxides for energy systems 2016.05.23 68578
177 <3/14> Proto-neutron star 2012.03.08 68403
176 <6/10(수) 오후4:30분> Closing in on the Axion Dark Matter hypothesis 2015.06.03 68371
175 <3/13> Quantum computing using solid state nano-devices 2013.03.08 68298
174 <8/29(토)> 세미나 개최 안내 2015.09.01 68284
173 <10/24> Dung-hai Lee 교수와의 간담회 2012.10.23 68246
172 <6/24(Fri.) 1:30pm>Emergent geometry from field theory: Wilson's renormalization group revisited 2016.06.20 68032
171 <11/14> Next Generation LED 2012.11.08 67809
170 <May.1(Wed.)> Introduction of AMS Application 2019.04.24 67494
169 <12/11> Is Nature Natural? 2013.12.05 67469
168 <3/22> 석학초청 특별강연 – Pyeongyang Advances Its Nuclear Program 2012.03.07 67401