|일시||June 22 (Fri.), 04:00 PM|
|연사||Dr. Daniel Sando|
Univ. of New South Wales, Sydney
Multiferroics – materials with coexisting ferroic orders such as ferroelectricity and (anti)-ferromagnetism – are presently under intense study by virtue of their promise in next-generation data storage devices. Bismuth ferrite (BiFeO3– BFO) is one of the very few that orders above room temperature. In the bulk, BFO is rhombohedral (R), and in thin films  its properties are sensitive to strain [2,3]. The discovery of the epitaxially-stabilized “super tetragonal phase” of BFO (T-BFO)  incited a flurry of research activity focused on understanding the phase transition and its possible functionalities . T-BFO is also multiferroic, with large ferroelectric polarization and antiferromagnetic order , and the strain relaxation-induced T/R phase mixtures and their exceptional piezoelectric responses  continue to intrigue and motivate researchers. A particularly important characteristic of this phase mixture is the interconversion between the R,T phases with an applied electric field . Since the oxygen configuration of the R and T polymorphs is different , the electronic, magnetic, and optical properties can thus be dynamically modulated. An additional rather crucial (and thus far underexplored) aspect of mixed R/T BFO is the role of chemistryin the formation of the metastable T-phase. Since T-BFO is typically fabricated by pulsed laser deposition, growth parameters can be used as a strong handle to tailor film properties and functionalities.
Here I will describe our work on understanding the influence of strain and growth conditions on the optical, magnetic, and ferroelectric properties of BFO films. I will also show that by precisely controlling fabrication conditions, the formation of the mixed R/T phases in BFO films can be completely suppressed for thicknesses above 70 nm. Such an intriguing result is useful for applications where thicker pure T-BFO films are needed, such as for measuring the expected giant polarization, or for precisely controlling the proportions of the various phases. Finally, through analysis of a large set of epitaxial films, it will be shown that the optical band gap of BFO is rather insensitive to a host of growth and processing parameters . Combined with the numerous other functionalities of this material, one can envisage multifunctional devices, for example, that harvest mechanical and solar energy, or to enhance magnetoelectric coupling at these multiferroic phase boundaries.
 Sando et al., J. Phys: Condens. Matt. 26, 473201 (2014).
 Infante et al., PRL 105, 057601 (2010).
 Sando et al., Nat. Mater. 12, 641 (2013).
 Bea et al., PRL 102, 217603 (2009).
 Sando et al., Appl. Phys. Rev. 3, 011106 (2016).
 Zeches et al., Science 326, 977 (2009).
 Sando et al., Adv. Opt Mater. 6, 1700836 (2018).
Department of Physics, KAIST
|320||Feb. 2(Tue) 2:30 PM||Zoom||Prof. Sangsik Kim (Texas Tech University, USA)||Quantum- & Nano-Photonics 세미나(Integrated Nanophotonics with Metamaterials, Microcomb, and Atomic Systems)|
|319||Dec.10(Thu), 01:55 PM||Zoom||Yin Wen (University of Tokyo)||Consistency of Boltzmann equation and light dark matter from inflaton decay|
|318||Dec.9(Wed), 10:00AM||Zoom||Prof. Andrew Geraci (Northwestern University)||Searching for the QCD axion with the ARIADNE experiment|
|317||December 2(Wed), 10:00AM||Zoom||Prof. Rakshya Katiwada (Illinois Institute of Technology)||Recent progress in Axion Dark Matter eXperiment (ADMX) technology|
|316||Sep. 11(Fri), 14:00~||zoom||이관형교수/SNU, 이상윤교수/GIST||SRC Seminar|
|315||Apr. 27, 2017 (Thu) 4:00 pm||Seminar Room(#1323, E6-2)||Prof.Donghan Lee (Chungnam National Univ.)||반도체 양자점을 이용한 단광자 광원|
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|313||2017/03/06 - 05/29||Seminar Room 1501||이종봉 박사 (POSTECH) 외||Spring 2017: Physics Colloquium|
|312||2017/03/21 - 06/08||Seminar Room 1323||조길영 박사(KAIST) 외||Spring 2017: Physics Seminar Serises|
|311||July 2. 2018 (Monday) 3:00 PM||Seminar Room (C303), Creation Hall (3F), KAIST Munji Campus||Dr. Peter Winter (Argonne National Laboratory)||High Precision Magnetic Field Measurement for the Muon g-2 Experiment|
|310||Thursday, December 14, 2017 at 3:00 pm||Seminar Room (C303), Creation Hall (3F), KAIST Munji Campus||Chunglee Kim (KASI)||Exploring the Universe via GWs in the era of multi-messenger astronomy|
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|308||Nov. 1 (Tue.) 2:30 pm||Seminar Room #1323(E6-2)||Prof. Youngjoon Kwon, Yonsei Univ.||Search for dark sector particles in the B-factory experiments|
|307||2019/09/18 - 12/5||Seminar Room #1323||Prof. David Schuster and etc.||Fall 2019: Physics Seminar Serises|
|306||July 26, 2018 at 14:00||Room 5318, KAIST Natural Sciences Lecture Hall(E6).||Manki Kim (Department of Physics, Cornell University)||Inflation in String Theory and Backreaction|
|305||July 27, 2018 at 15:00||Room 5318, KAIST Natural Sciences Lecture Hall(E6).||Dr. Hyejung Kim(Technische University Dresden)||Muon g-2 in the 2HDM and MSSM: comprehensive numerical analysis and absolute maxima|
|304||July 13, 2018 at 14:00||Room 5318, KAIST Natural Sciences Lecture Hall(E6).||Prof. Ian Lewis (The University of Kansas, Department of Physics & Astronomy)||Loop Induced Single Top Partner Production and Decay at the LHC|
|303||Thursday, July 12, 2018 at 17:00||Room 5318, KAIST Natural Sciences Lecture Hall(E6)||Dr. Jae Hyeok Yoo (University of California, Santa Barbara, Department of Physics)||The MilliQan Experiment: Search for Milli-Charged Particles at the LHC|
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|301||April 5th 2017, 12:00 ~ 13:00||Room 101, Creative Learning Bldg.(E11)||Prof. Wonho Choe(Dept. of Physics),Prof. Young-chul GHIM(Dept. of Nuclear & Quantum Engineering)||2017년 4월 첫수 융합포럼 개최 안내(물리학과 & 원자력 및 양자공학과 공동 개최)/The First Wednesday Multidisciplinary Forum in April 2017 organized by Dept. of Physics & Dept. of Nuclear & Quantum Engineering|