|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
|공지||2019/09/18 - 12/5||Seminar Room #1323||Prof. David Schuster and etc.||Fall 2019: Physics Seminar Serises|
|공지||2019/09/02 - 12/09||Seminar Room 1501||이호성 박사 (한국표준과학연구원) and etc.||Fall 2019: Physics Colloquium|
|154||July 2, 2020 (Thursday)||Zoom Video Conference Seminar||Dr. Emmanuel Flurin (CEA Saclay)||An irreversible qubit-photon coupling for the detection of itinerant microwave photons|
|153||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|
|152||July 10 (Wed.), 04:00 PM-||Academic Cltural Complex (E9) 5층 스카이라운지||Prof. Sidney Nagel/Young-Kee Kim||Public Lectures|
|151||Jul. 28 (Thu.) 4PM||#1323(E6-2. 1st fl.)||Prof. Johannes Pollanen, Jerry Cowen Chair of Experimental Physics at Michigan State University||Low Dimensional Electrons: On the Road to Hybrid Quantum Systems|
|150||Jul. 08 (Fri.) 2PM||#1323(E6-2. 1st fl.)||Dr. Junhyun Lee, Harvard University||Electronic quasiparticles in the quantum dimer model|
|149||Jul. 08 (Fri.) 11:00 AM||#1323(E6-2. 1st fl.)||Dr. Michael Lawler(Binghampton Univ. / Cornell Univ.)||Isostatic magnetism|
|148||Jul. 07 (Thu.) 2PM||#1323(E6-2. 1st fl.)||Dr. Eun Ah Kim, CORNELL UNIV.||Let there be topological superconductors|
|147||Jul 3rd, 2019 (Wed)||E6-2, 2501||Kyung Soo Choi||Many-body quantum electrodynamis (QED) with atoms and photons: A new platform for quantum optics"|
|146||January 23, 2019||Rm. C303, Creation Hall (3F), Munji Campus||Mikko Mottonen||Ultrasensitive Microwave Bolometer: Opportunity for Axion Detectors|
|145||January 17 (Fri), 4:00 PM||#1323, E6-2||Hiroki Ikegami||Symmetry Breaking and Topology in Superfluid 3He|
|144||Jan.9 (Wed.), 04:00 PM||E6-2. 2nd fl. #2501||Dr. Heung-Sik Kim||Molecular Mott state in the deficient spinel GaV4S8|
|143||JAN. 7 (Mon), 03:00 PM||E6-2. 2st fl. #2501||Dr. Byoung min Kang||Many-Body Invariants for Multipoles in Higher-Order Topological Insulators|
|142||February 21 (Thu.), 16:00 PM||#5313, E6-2||Prof. Diptimoy Ghosh||B-meson charged current anomalies - Theoretical status|
|141||February 20 (Thu), 4:00 PM||#1323, E6-2||Seunghyun Khim||Unconventional superconductivity in the locally non-centrosymmetric heavy-fermion CeRh2As2|
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|139||February 12(Web.)||E6-2, #5318||Prof. Kunio Kaneta||From inflation to new weak-scale|
|138||Feb. 25 - Jun 3||Rm. 1501 (E6)||Spring 2019: Physics Colloquium|
|137||Feb. 12 (Mon), 3:00pm||#C303, (Creation Hall 3F, KAIST Munji Campus)||Dr. Byeongsu Yang, Kamioka Observatory, Univ. of Tokyo||The recent result of XMASS Experiment|
|136||Feb. 1 (Wed.), 2p.m.||#1323(E6-2. 1st fl.)||Dr. Michihisa Yamamoto, Department of Applied Physics, The University of Tokyo||Quantum electron optics using flying electrons|
|135||December 5 (Thu.), 16:00 PM||#1323, E6-2||Prof. Soon-Hong Kwon||Subwavelenth Photonic Devices: From Single Photon Sources to Solar Cell|