|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
|200||Jun 28, 14:00||E6-2, #1322||Dr. Bongjae Kim, Dr. Sooran Kim, Dr. Jeongwoon Hwang||1st Research-exchange meeting of computational material physics|
|199||Sep. 02(Fri) 2:30 PM||E6-2(1st fl.), #1323||Dr. Yong-Hyun Kim,Graduate School of Nanoscience and Technology, KAIST||Nanoscale Thermal Physics: Seebeck Effect and Nanoscale Friction|
|198||Sep. 02(Fri) 4:00 PM||E6-2(1st fl) #1323||Dr. Yong-Joo Doh, Department of Physics and Photon Science, GIST||Quantum Electrical Transport in Topological Insulator Nanowires|
|197||Jan. 17(Mon) - 21 (Fri), 2-4pm||E6-2 Room 2502||Dr. Donghui Jeong (Penn State University)||Five Lectures on Observational Probes of Dark Energy|
|196||Nov. 12 (Thu.) 4:00 PM||E6-2 1323||김영덕 (Young Duck Kim) 교수||2020 가을학기 광학분야 특별세미나|
|195||Aug. 8th (Mon), 14:00||E6-2 #2502||Prof. Soonwon Choi(MIT)||Classical Shadow Tomography for Analog Quantum Simulators|
|194||Sep. 29th(Thu), 4PM||E6-2 #1323 (1st floor)||Dr. Sangyoon Han, Department of Physics, KAIST||Large-scale Silicon Photonic MEMS Switches|
|193||June 3(Fri.) 11:00||E6-2 #1323||Prof. Gil Young Cho (Department of Physics, POSTECH)||(응집물리 세미나) Theoretical Investigation of Exotic Quantum States in Low-dimensional Materials|
|192||Oct 23 (Fri.), 14:00 PM||E6-2 #1323||Prof. Ivan Savenko (University of Science and Technology & IBS PCS)||Plasmon spectroscopy of low-dimensional superconductors in fluctuating regime|
|191||Oct. 10(Tue) 4PM||E6-2 #1323||김성웅 교수 (성균관대학교 에너지과학과)||Discovery of New 2D Materials with Diverse Physical Properties|
|190||DEC. 26 (Wed), 04:00 PM||E6-1. 3rd fl. #3434||Y. Kim, A. Go, K. Hwang and E.-G. Moon||Informal Workshop on Topology and Correlation|
|189||October 24 (Wed.), 10:30 AM||E6-1, Lecture Room 1501(1F)||Prof. Kerry J. Vahala||Photonic integration of next-generation clocks and Hertz-absolute-accuarcy optical frequenncy synthesizers|
|188||Aug.12(Fri.) 10:00AM, 2022||E6-1 #1323||Dr. Moon Jip Park (Center for Theoretical Physics of Complex Systems, IBS)||Twisted Bilayer Magnets|
|187||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|
|186||April 08(Fri.) 11:00||E6-1 #1323||Prof. Se-Young Jeong (Optics and Mechatronics Engineering , Pusan National University)||(응집물리 세미나) Flat-surface-assisted physical phenomena occurring in single crystal metal thin film|
|185||Mar. 25(Fri.) 11:00||E6-1 #1323||Prof. Ara Go (Department of Physics, Chonnam National University)||(응집물리 세미나) Hund's metallicity in ruthenate systems|
|184||2014/12/22, 2PM||E6, Rm1319||Prof. Changbong Hyeon (KIAS)||Dynamics of molecular motors: Power stroke vs Brownian ratchet|
|183||2016/03/07-06/13||E6, 1501||Prof. David Helfman(KAIST) 외||Physics Colloquium : 2016 Spring|
|182||2015/09/07-12/01||E6, 1501||문은국 교수(KAIST) 외||Physics Colloquium : 2015 Fall|
|181||2009/02/23-05/04||E6, 1501||안종현교수(성균관대) 외||Physics Colloquium : 2009 Spring|