|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|
|129||November 5 (Tue.), 4:00 PM||#1323, E6-2||Dr. Shik Shin||Study on nanomaterials by the development of ultrahigh resolution laser-photoelectron microscopy (PEEM)|
|128||November 20 (Wed.), 4:00 PM||#5302, E6-2||Dr. Shigeyuki Ishida||Correlation between superconducting transition temperature and critical current density in irradiated iron-based superconductors|
|127||February 13th (Thur.), 16:30 PM||E6-6, #119||Dr. Seyoon Kim(University of Wisconsin-Madison)||Enhanced Light-Matter Interactions in Graphene with Noble Metal Plasmonic Structures|
|126||October 31 (Thu.), 10:00am||#1323 (E6-2, 1st fl.)||Dr. Seung-Sup Lee||Kondo meets Hubbard: Impurity physics for correlated lattices|
|125||Apr. 09 (Mon.), 11:00 AM||E6-2. 1st fl. #1323||Dr. Seung-Sup B. Lee||Doublon-holon origin of the subpeaks at the Hubbard band edges|
|124||October 29 (Tue.), 4:00pm||#1323 (E6-2, 1st fl.)||Dr. Seung-Joo Lee||Particles and Gravity via String Geometry|
|123||Jun. 01 (Fri.), 11:00 AM||E6-2. 1st fl. #1323||Dr. Seung Sae Hong||Topological phases in low-dimensional quantum materials|
|122||Mar. 29 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. Seung Hyub Baek||Epitaxial Multifunctional Oxide Thin Films for Novel Electronics|
|121||2016/1/26, 2PM||E6-2, #1323||Dr. Sergei V. Kalinin (Center for Nanophase Materials Sciences, Oak Ridge National Laboratory)||Electrochemistry on Nano- and Atomic Levels: Scanning Probe Microscopy Meets Deep Data|
|120||Apr. 19 (Fri.), 04:00 PM||E6-2. 1st fl. #1323||Dr. Seok Kyun Son||Graphene and hBN heterostructures|
|119||June 17 (Mon.), 10:30 AM||#1323, E6-2||Dr. See-Hun Yang||Chiral Spintronics|
|118||2015/07/15, 2PM||E6-2,1323||Dr. Se Young Park(Rutgers Univ.)||Electronic and optical properties of titanate-based oxide superlattices|
|117||Sep. 29th(Thu), 4PM||E6-2 #1323 (1st floor)||Dr. Sangyoon Han, Department of Physics, KAIST||Large-scale Silicon Photonic MEMS Switches|
|116||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|
|115||2015/12/03, 4PM||E6-2, #1323||Dr. Sang-Yun Lee (3rd institute of Physics, University of Stuttgart, Germany)||Hybrid solid state spin qubits in wide bandgap semiconductors|
|114||Jun. 2 (Fri.), 4:00 PM||#1323 (E6-2. 1st fl.)||Dr. Sang Wook Kim||Maxwell's demon in quantum wonderland|
|113||Nov. 9 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. Pilkyung Moon||Moiré superlattices – from twisted bilayer graphene to quasicrystal|
|112||2015/10/16, 3PM||E6-2, 5th fl. #5318||Dr. Pierre Pugnat , (CNRS-LNCMI)||High Magnetic Fields to Probe the sub-eV range of Particle/Astroparticle Physics - From the OSQAR experiments at CERN up to new perspectives at LNCMI-Grenoble|
|111||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|
|110||Jun. 1(Wed) 10:30 AM||BK21 Conference Room (#1318, E6-2)||Dr. Noriaki Horiuchi, Editor, Nature Photonics||Welcome to Nature Photonics|