|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|
|279||Nov. 20 (Fri.), 04:00 PM||Online||Dr. Dohun Kim||Coherent control of field gradient induced quantum dot spin qubits|
|278||Nov. 20 (Fri.), 02:30 PM||Online||Dr. Doohee Cho||Lumpy Cooper pairs in an iron-based superconductor|
|277||Dec. 11 (Fri.), 02:30 PM||online||Myung Hwa Jung(Sogang Univ.)||Antisymmetric interlayer exchange coupling in magnetic multilayers|
|276||Dec. 11 (Fri.), 04:00 PM||online||Hyobin Yoo(Sogang Univ.)||Atomic and electronic reconstruction at van der Waals interface in twisted 2D materials|
|275||Dec.23(Wed), 10:00~16:00||Online||Prof. YongKeun Park (KAIST) and etc.||Online workshop for Quantitative Phase Imaging|
|274||2016/09/05-12/12 4PM||Natual Scien Bldg.(E6)m #1501||Yeong Kwan Kim 외||Physics Colloquium : 2016 Fall|
|273||May 19, 2016 (Thur.) 3PM||May 19, 2016 (Thur.) 3PM,||Dr. Michael Betz, CERN||The CERN Resonant WISP Search: Development, Results and Lesson-Learned|
|272||2017.1.9(Mon), 4PM||Lecture Hall, College of Natural Sciences [#1501,E6-2]||Prof. John Michael Kosterlitz, Brown University||Topological Defects and Phase Transitions"|
|271||4월 18일(월), 15:30~||KI빌딩(E4), 강의실 B501 (5F)||Prof. Robert A. DiStasio Jr. (Cornell University)||First Principles Approaches for Intermolecular Interactions: From Gas-Phase Dimers to Liquid Water and Molecular Crystal Polymorphism|
|270||2014/05/28, PM5||KI Building, Matrix Hall||이웅범 대표이사(LG이노텍)||부품소재산업이 미래다|
|269||Aug. 4, 2016 (Thu.), 2:30 pm||KAIST Natural Science Building (E6-5), EDU 3.0 Room(1st fl.)||Prof. Argyris Nicolaidis||Relational Logic (with applications to Quantum Mechanics, String Theory, Cosmology, Neutrino Oscillations, Statistical Mechanics)|
|268||April 4, 2016 (Mon) - April 8, 2016 (Fri)||KAIST Natural Science Building (E6-2), RM #4314||Dr. Fritz Caspers (CERN)||Radio frequency engineering|
|267||2015/10/14, 6PM||KAIST Munji Campus Supex Hall||이창환 교수 (부산대학교 물리학과)||인터스텔라 영화 속의 물리|
|266||#1323(E6-2. 1st fl.)||Jul. 10th (Mon), 4pm||Dr. Duk Young Kim Los Alamos National Laboratory||“Intertwined Orders in a Heavy-fermion metal”|
|265||April 6, 2017 (Thu), 4:00 pm||IBS CAPP seminar room, Creation Hall (3F), KAIST Munji Campus||Prof. Youngjoon Kwon (Yonsei University)||For whom the Belle tolls|
|264||Oct. 16 (Fri.), 02:30 PM||https://kaist.zoom.us/j/89198078609||Dr. Chulki Kim||Nanoscale magnetic resonance detection towards nano MRI|
|263||Oct. 16 (Fri.), 04:00 PM||https://kaist.zoom.us/j/89198078609||Dr. Daesu Lee||Hidden room-temperature ferroelectricity in CaTiO3 revealed by a metastable octahedral rotation pattern|
|262||Oct 9 (Fri), 09:00 AM||https://kaist.zoom.us/j/85161896513?pwd=U3pwWFFZaWVRamxDZUR5REhNeVk0UT09||Prof. Tim Hsieh (Perimeter Institute)||Quantum Many-Body Simulation|
|261||October 15, 5:00pm||https://bit.ly/3ndIiJn||Dr. Samuli Autti||Time crystals, quasicrystals, and time crystal dynamics in the superfluid universe|
|260||May 13 (Fri.) 4 PM||E6. #1501(1st fl.)||Dr. Hosub Jin, Dept. of Physics, UNIST||Graphene analogue in (111)- BaBiO3 bilayer heterostructures for topological electronics|