|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|
|313||2018년 9월 7일 (금), 3PM||학술문화관 (E9), 2층 양승택 오디토리움||Prof. Martin Head-Gordon, UC Berkeley||Recent developments in density functional theory: From new functionals to the nature of the chemical bond|
|312||5월 17일(화), 11:00 ~ 12:00||창의학습관(E11), 406호||방준혁 박사(Korea Basic Science Institute, KBSI)||The CERN Resonant WISP Search: Development, Results and Lesson-Learned|
|311||Dec. 13-14(Wed.-Thu.) 13:30 PM||자연과학동 대형강의실 (1501호)||장기주 교수 외 9명||KAIST-KIAS Joint Workshop in Theoretical Sciences 개최|
|310||August 1, 2018 at 11:00AM||양분순 빌딩 (E16-1) 207호||이대열 교수, 예일대 석좌교수||Future of AI: Is the brain a computer?|
|309||Aug. 17(Mon), 20:00~||Zoom webinar||Mark D. Stiles (NIST, USA)||Using magnetic tunnel junctions to compute like the brain|
|308||Aug, 25(Tue), 20:00~||Zoom webinar||Mark D. Stiles (NIST, USA)||KAIST Global Forum for Spin and Beyond (Second Forum)|
|307||Sep. 14(Mon) 17:30~||Zoom webinar||Teruo Ono (Kyoto U. Japan)||KAIST Global Forum for Spin and Beyond (Third Forum)|
|306||Sep. 22nd 9:30 AM||Zoom webinar||Prof. Xu Yi (Univ. of Virginia, USA)||Physics and applications of soliton microcombs(Quantum- & Nano-Photonics)|
|305||Sep.28. 5:30 pm||Zoom webinar||Burkard Hillebrands (TU Kaiserslautern, Germany)||KAIST Global Forum for Spin and Beyond(Fourth Forum)|
|304||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|
|303||Sep. 24(Thu), 09:00~, Sep. 24(Thu), 16:00 ~||Zoom Video||Akash V. Dixit (University of Chicago), Dr. Boris Ivanov (Novosibirsk State Technical University)||(CAPP/IBS)Searching for Dark Matter with a Superconducting Qubit , Cryogenic Microwave Circuit Development at the NSTU|
|302||Sep. 11(Fri), 14:00~||zoom||이관형교수/SNU, 이상윤교수/GIST||SRC Seminar|
|301||December 2(Wed), 10:00AM||Zoom||Prof. Rakshya Katiwada (Illinois Institute of Technology)||Recent progress in Axion Dark Matter eXperiment (ADMX) technology|
|300||Apr. 27, 2017 (Thu) 4:00 pm||Seminar Room(#1323, E6-2)||Prof.Donghan Lee (Chungnam National Univ.)||반도체 양자점을 이용한 단광자 광원|
|299||2017/03/06 - 05/29||Seminar Room 1501||이종봉 박사 (POSTECH) 외||Spring 2017: Physics Colloquium|
|298||2017/03/21 - 06/08||Seminar Room 1323||조길영 박사(KAIST) 외||Spring 2017: Physics Seminar Serises|
|297||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|
|296||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|
|295||Jun. 14 (Tue) 4PM||Seminar Room (#2502, 2nd fl.)||Young-Sik Ra, Université Pierre et Marie Curie||Photonic quantum network based on multimode squeezed vacuums and single-photon subtraction|