|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||Sep.22 2022||E6-1 #1323||2022 가을학기 응집물리 및 광학 세미나 전체 일정|
|163||MAR. 26 (TUE), 0300 PM||E6-2. 2st fl. #2501||Prof. Jung Hoon Han||Consideration of thermal Hall effect in frustrated and un-frustrated quantum magnets|
|162||Mar. 29 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. Seung Hyub Baek||Epitaxial Multifunctional Oxide Thin Films for Novel Electronics|
|161||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|
|160||Mar. 2nd (Thu), 4:00 p.m||#1323(E6-2. 1st fl.)||Dr. Jonathan Denlinger, Lawrence Berkeley National Lab||“Progress in the comparison of ARPES to DMFT for d and f strongly correlated electron systems”|
|159||Mar25(Thur), 04:00PM||Online Seminar (Zoom)||Prof. Atsushi Tokiyasu (Tohoku Univ.)||Search for dark matter axion with Rydberg atoms|
|158||March 18(Fri.) 11:00||Online seminar||Dr. Dirk Wulferding (IBS-Center for Correlated Electron Systems, Seoul National University, Seoul)||(응집물리 세미나) Illuminating exotic states of matter: Raman spectroscopy as an experimental tool to characterize quantum spin liquids|
|157||May 20(Fri.) 11:00||E6-1 #1323||Prof. Kwanpyo Kim (Department of Physics, Yonsei University)||(응집물리 세미나) Exploration of new polymorphs in van der Waals crystals|
|156||May 1 (Wed), 4:00 PM||#1323, E6-2||Dr. Sungkyun Choi||Raman and x-ray scattering study on correlated electron systems: two case examples|
|155||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|
|154||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|
|153||May 13 (Fri.), 1:30 PM||E6. #1501(1st fl.)||Dr. Young-Woo Son, Dept. of Physics, KIAS||Aperiodic crystals in low dimensions|
|152||May 16, 2016 (Mon) 4PM||#1323(E6-2, 1st Fl.)||Dr. Daniel Bowring , Fermi National Accelerator Laboratory||Tuning microwave cavities with biased nonlinear dielectrics for axion searches|
|151||May 19 (Thu) 4PM||#1323(E6-2, 1st fl.)||Dr. Heedeuk Shin, POSTECH||Nonlinear/quantum optical effect in silicon nano-photonics|
|150||May 19, 2016 (Thur.) 3PM||May 19, 2016 (Thur.) 3PM,||Dr. Michael Betz, CERN||The CERN Resonant WISP Search: Development, Results and Lesson-Learned|
|149||May 2 (Thu.), 4:00 PM||#1323, E6-2||Prof. Joon Ik Jang||Anomalous optical properties of halide perovskites|
|148||May 21 (Tue.), 4:00 PM||#5318, E6-2||임준원 박사||Classification of flat bands according to the band-crossing singularity of Bloch wave functions|
|147||May 24 (Fri.), 16:00 PM||#1323, E6-2||Prof. Soonjae Moon||Infrared spectroscopy study on metal-insulator transitions in layered perovskite iridates|
|146||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|
|145||May 27,(Fri), 11:00 AM||Online seminar||Prof. Gray Rybka(University of Washington)||Current Status and Future Plans of ADMX|
|144||May 29 (Tue.), 04:00 PM||#1323, E6-2||Prof. Jae-Won Jang||Investigation on metal nanostructure/semiconductor junction and its applications|