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 1079573
687 <Oct. 12(Wed.)>Neurodegenerative Diseases from the Chemical Force Point of View new 2022.10.05 0
686 <Oct. 5(Wed.)>“사라진 중성미자를 찾아서” 2022.09.29 35
685 <Sep. 21(Wed.)>Dynamics and thermodynamics of bimolecular reactions at aqueous-nonaqueous interfaces 2022.09.15 104
684 <Sep. 14(Wed.)>The Next Generation of Photonic Sources – Light-Emitting Devices 2022.09.08 209
683 <Sep. 7(Wed.)>Flavor of particles, as a key for New physics 2022.09.01 273
682 2022학년도 2학기 콜로퀴움 일정 2022.06.22 1359
681 <July 8(Fri.)>Intertwined magnetism and charge density wave in a kagome metal 2022.06.03 1497
680 <Apr. 27(Wed.)> I) A few first questions by me. II) ‘Topotactic resistance switching RAM’의 최초 발견 2022.04.20 1540
679 <May 18(Wed.)>Magnetoresistance and Hall effects of Fe5Sn3 single crystals 2022.05.12 1580
678 <May 4(Wed.)>Recent progress in the study of topological phases of matter 2022.04.27 1589
677 <Apr. 20(Wed.)> 반도체 공정용 플라즈마 물리 2022.04.14 1604
676 <May. 10(Tue.)>Longitudinal magnon decay in the quasi-two-dimensional antiferromagnet in Ba2FeSi2O7 2022.05.09 1958
675 <May. 3(Tue.)>Anomalous Hall signatures of nonsymmorphic nodal lines in the doped chromium chalcospinel CuCr2Se4 2022.04.19 2069
674 <Mar. 16(Wed.)> 현세대/차세대 이차전지 기술 동향 및 전망 2022.03.02 2098
673 <Mar. 30(Wed.)> Two-dimensional Semiconductors and their applications 2022.03.23 2164
672 <Apr. 6(Wed.)> Holographic Flat Panel Displays 2022.03.30 2205
671 <May 11(Wed.)>Key Nuclear Experimental Studies to Find the Origin of Elements 2022.05.04 2482
670 <Mar. 2(Wed.)>Introduction to high-energy nuclear physics 2022.02.24 2739
669 <Jan. 27(Thu.)>Emulating twisted double bilayer graphene with a multiorbital optical lattice 2022.01.18 2929
668 <Mar. 23(Wed.)> Next-generation artificial intelligence devices and physics 2022.03.16 3247