|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|
|206||Mar. 29 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. Seung Hyub Baek||Epitaxial Multifunctional Oxide Thin Films for Novel Electronics|
|205||Mar. 29 (Fri.), 04:00 PM||E6-2. 1st fl. #1323||Dr. Taeyoung Choi||Coherent Quantum Control and Magnetism on atoms – Trapped ion and ESR STM|
|204||Apr. 19 (Fri.), 04:00 PM||E6-2. 1st fl. #1323||Dr. Seok Kyun Son||Graphene and hBN heterostructures|
|203||Apr. 19 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. YoungWoo Nam||A family of finite-temperature electronic phase transitions in graphene multilayers|
|202||Sep. 10 (Tue.), 03:00 PM||E6-2. 1st fl. #1323||Dr. Mikhail Kiselev||Two-Stage Kondo Effect|
|201||Sep. 27 (Fri.), 04:00 PM||E6-2. 1st fl. #1323||Dr. Jindong Song||0D/1D/2D/3D III-V materials grown by MBE for Optelectronics|
|200||Sep. 27 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. Joon Sue Lee||Spin-charge conversion in topological insulators for spintronic applications|
|199||Nov. 1 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. YoungWook Kim||Squeezing the best out of 2D materials|
|198||Nov. 1 (Fri.), 04:00 PM||E6-2. 1st fl. #1323||Dr. Ju-Jin Kim||Electron transport through weak-bonded contact metal with low dimensional nano-material|
|197||Apr. 5 (Tue.), 4PM||E6-2. 1st fl. #1322||Dr. Ara Go, Columbia University||A new impurity solver for multi-orbital systems: adaptive truncation of the Hilbert space|
|196||2015/09/07, 3PM||E6-2. 1st fl. #1318||Dr. Jasbinder Sanghera (U.S. Naval Research Laboratory (NRL))||Advanced Optical Materials and Devices at NRL|
|195||4pm, Sep. 21 (Wed.||E6-2. #2502(2nd fl.)||Dr. Henrik Johannesson , University of Gothenburg (Sweden) and Beijing Computational Science Research Center (China)||Entanglement probe of two-impurity Kondo physics|
|194||Sep. 29 (Thu), 4:00 PM||E6-2. #2501(2nd fl.)||Dr. Minu Kim, Institute for Basic Science, Seoul National University||Exploring the phase diagram of BaBiO3: epic voyage of just another bad trip?|
|193||May 11 (Wed.), 4 PM||E6-2. #1323(1st fl.)||Dr. Bumjoon Kim, Max Planck Institute for Solid State Research||The quest for novel high-temperature superconductors---Prospects and progress in iridates|
|192||May 24 (Tue) 4 PM||E6-2. #1323(1st fl.)||Dr. Euyheon Hwang, SKKU Advanced Institute of Nanotechnology, Sung Kyung Kwan University||Electronic and magnetic properties of 2D transition-metal thiophosphates and tunability of magnetic order with carrier density|
|191||Oct. 07 (Fri), 1:30 PM||E6-2. #1323(1st fl.)||Dr. Suk Bum Chung, IBS-CCES , Seoul National University||“Symmetry and topology in transition metal dichalcogenide?”|
|190||Oct. 07 (Fri), 4:00 PM||E6-2. #1323(1st fl.)||Dr. Choong Hyun Kim,IBS-CCES, Seoul National University||“Tilt engineering of 4d and 5d transition metal oxides?”|
|189||Nov. 04 (Fri), 1:30 PM||E6-2. #1323(1st fl.)||Dr. Jonghyun Song, Department of Physics, Chungnam National University||Exotic phenomena at oxide LaAlO3/SrTiO3 hetero-interface and their applications|
|188||Nov. 04 (Fri), 3:00 PM||E6-2. #1323(1st fl.)||Dr. Dohun Kim, Department of Physics and Astronomy, SNU||Quantum information experiments using few electron spins in semiconductors|
|187||Nov. 10th(Thu) 4 p.m.||E6-2. #1323(1st fl.)||Prof. Min Seok Jang, Electrical Engineering, KAIST||Low Dimensional Active Plasmonics and Electron Optics in Graphene|