|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|
|261||Feb.17(Wed)~19(Fri), 09:00~11:00AM||Online||Prof. Subir Sachdev (Harvard University)||석학 대중 강연 및 강의 시리즈|
|260||April 4 (Thu.), 16:00 PM||#1323, E6-2||Prof. Su-Hyun Gong||Chiral spin-photon interaction at nanoscale|
|259||May 24 (Fri.), 16:00 PM||#1323, E6-2||Prof. Soonjae Moon||Infrared spectroscopy study on metal-insulator transitions in layered perovskite iridates|
|258||December 5 (Thu.), 16:00 PM||#1323, E6-2||Prof. Soon-Hong Kwon||Subwavelenth Photonic Devices: From Single Photon Sources to Solar Cell|
|257||October 4 (Thu.), 16:00 PM||#1323, E6-2||Prof. Soo Jin Kim||Engineering light absorption in an ultrathin semiconductor metafilm|
|256||July 10 (Wed.), 04:00 PM-||Academic Cltural Complex (E9) 5층 스카이라운지||Prof. Sidney Nagel/Young-Kee Kim||Public Lectures|
|255||2019. 7. 16(화)||Rm. 1323 (E6-2)||Prof. Sidney Nagel||2019 Physics Distinguished Lecture|
|254||December 18 (Tue.), 4:00 PM||#1323, E6-2||Prof. Shin-ichi Uchida||Road to Higher Tc Superconductivity|
|253||June 14, 2016 (Tue) 3PM||#1323 (E6-2 1st fl.)||Prof. Seungyong Hahn, Florida State University||No-Insulation High Temperature Superconductor Magnet Technology for Compact, Reliable, and Low-Cost High Field DC Magnets|
|252||November 21 (Wed.), 15:00 PM||#1323, E6-2||Prof. Seongshik Oh||Engineering topological quantum physics at the atomic scale|
|251||October 29 (Tue.), 10:00am||#1323 (E6-2, 1st fl.)||Prof. Se Kwon Kim||Unconventional Spin Transport in Quantum Materials|
|250||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)|
|249||NOV. 23 (Fri), 03:00 PM||E6-2. 2st fl. #2501||Prof. Sang-Jin Sin||Entanglement string and Spin Liquid with Holographic duality|
|248||2018. 6. 22 10:00am ~ 11:50am||E6-6, Lecture Room 119 (1F)||Prof. Sang Bok Lee, Dept. of Chemistry and Biochemistry, Univ. of Maryland||Success in Research Career|
|247||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|
|246||December 2(Wed), 10:00AM||Zoom||Prof. Rakshya Katiwada (Illinois Institute of Technology)||Recent progress in Axion Dark Matter eXperiment (ADMX) technology|
|245||Nov 17th 12:00 PM||Online(Zoom)||Prof. Qiang Lin (Univ. of Rochester, USA)||Quantum- & Nano-Photonics" 세미나 시리즈|
|244||October 15 (Tue.), 16:00 PM||#1323, E6-2||Prof. Pilkyung Moon||Moiré superlattices and graphene quasicrystal|
|243||Aug. 16 (Wed.), 4 PM||#1322 (E6-2. 1st fl.)||Prof. Noejung Park (UNIST)||Phonon-driven spin-Floquet valleytro-magnetism|
|242||August. 14th (Wed.), 4:00PM,||Rm. 1323, E6||Prof. Nicolas Treps||Quantum Optics, at the heart of quantum metrology and quantum information|