|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|
|308||Aug. 16 (Wed.), 4 PM||#1322 (E6-2. 1st fl.)||Prof. Noejung Park (UNIST)||Phonon-driven spin-Floquet valleytro-magnetism|
|307||Mar. 24 (Fri.), 4:00 PM||#1323 (1st fl. E6-2)||Dr. SangWook Lee||Graphene based nano electronics and nano electromechanics; focusing on precise control of nano structures for studying accurate physical properties|
|306||Mar. 24 (Fri.), 2:30 PM||#1323 (1st fl. E6-2).||Dr. MahnSoo Choi||Topological Dynamics|
|305||Nov. 3 (Fri.), 2:30 PM||#1323 (1st fl., E6-2.)||Dr. MinChul Lee(Department of Applied Physics, Kyung Hee Univ.)||Quantum Resistor-Capacitor Circuit with Majorana Edge States|
|304||Nov. 3 (Fri.), 4:00 PM||#1323 (1st fl., E6-2.)||Dr. SungDae Ji (Max Planck POSTECH/Hshinchu Center (MPK))||Expedition to the Kitaev Quantum Spin Liquid: Hunting for Majorana fermions|
|303||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|
|302||April 13 (Fri.), 10am||#1323 (E6-2, 1st fl.)||Dr. Sungkun Hong||Quantum meets Mechanics: from Quantum Information to Fundamental Research|
|301||April 11 (Wed), 1:30pm||#1323 (E6-2, 1st fl.)||Dr. Yongsoo Yang||Probing 3D Structure and Physical Properties of Materials at the Single-Atom Level|
|300||April 11 (Wed), 4:00pm||#1323 (E6-2, 1st fl.)||Dr. Young-Sik Ra||Non-Gaussian states of multimode light generated via hybrid quantum information processing|
|299||October 16 (Wed), 4:00pm||#1323 (E6-2, 1st fl.)||Dr. Jaewon Song||Emergent black holes and monopoles from quantum fields|
|298||October 29 (Tue.), 10:00am||#1323 (E6-2, 1st fl.)||Prof. Se Kwon Kim||Unconventional Spin Transport in Quantum Materials|
|297||October 29 (Tue.), 4:00pm||#1323 (E6-2, 1st fl.)||Dr. Seung-Joo Lee||Particles and Gravity via String Geometry|
|296||October 31 (Thu.), 10:00am||#1323 (E6-2, 1st fl.)||Dr. Seung-Sup Lee||Kondo meets Hubbard: Impurity physics for correlated lattices|
|295||Jun. 2 (Fri.), 4:00 PM||#1323 (E6-2. 1st fl.)||Dr. Sang Wook Kim||Maxwell's demon in quantum wonderland|
|294||Apr. 28 (Fri.), 04:00 PM||#1323 (E6-2. 1st fl.)||Dr. Minkyung Jung Research Institute, DGIST||Carbon nanotubes coupled to superconducting impedance matching circuits|
|293||July. 14 (Fri.), 3:00 PM||#1323 (E6-2. 1st fl.)||Dr. Jun Hyun Lee / University of Maryland||Chiral anomaly in disordered Weyl semimetals|
|292||Sep. 12 (Tue.), 4 PM||#1323 (E6-2. 1st fl.)||Prof. Yi. Zhou (The Zhejiang Univ.)||Exact Solution for the Interacting Kitaev Chain at Symmetric Point|
|291||Sep. 13 (Wed.), 4 PM||#1323 (E6-2. 1st fl.)||Prof. Yi. Zhou (The Zhejiang Univ.)||An Introduction to Quantum Spin Liquids|
|290||Sep. 26 (Tue.), 11AM||#1323 (E6-2. 1st fl.)||Dr. Yukiaki Ishida / ISSP, University of Tokyo||Time-resolved ARPES study of Dirac and topological materials|
|289||Nov. 28 (Tue.), 4:00 PM||#1323 (E6-2. 1st fl.)||Samindranath Mitra, Editor at Physical Review Letters||Physics after the lab and the desk: Your work in PRL|