|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|
|216||Sep. 15th (Thu) 1 PM||E6-2, #1323||Dr.Christopher Couzens(Kyunghee University)||AdS black holes: a review|
|215||May. 18(Wed), 4pm||E6-2. #1323 & Zoom||Dr.Heeyeon Kim (Rutgers University, Department of Physics and Astronomy)||Geometry, Algebra, and Quantum Field Theory|
|214||May. 19(Thu), 4pm||E6-2. #1323 & Zoom||Dr.Jay Hyun Jo (Yale University, Department of Physics)||Chasing Long Standing Neutrino Anomalies with MicroBooNE|
|213||May. 12(Thu), 4pm||E6-2. #1323 & Zoom||Dr.Philip Chang (University of California San Diego, Department of Physics)||New frontiers of electroweak physics at the LHC|
|212||Dec 27 (Fri), 3:00 PM||#5318, E6-2||Han Gyeol Suh||The superconducting order parameter puzzle of Sr2RuO4|
|211||December 27(Fri.), 15:00||E6-2,#5318||Han Gyeol Suh||The superconducting order parameter puzzle of Sr2RuO4|
|210||September 26 (Thu.), 16:00 PM||#1323, E6-2||Han Seb Moon||Entanglement Swapping with Autonomous Polarization-Entangled Photon-Pairs from Warm Atomic Ensemble|
|209||January 17 (Fri), 4:00 PM||#1323, E6-2||Hiroki Ikegami||Symmetry Breaking and Topology in Superfluid 3He|
|208||August 27 (Tue.), 4:00PM||Rm. 1323, E6||Hiroshi Eisaki||Critical current properties of Fe-based superconductors|
|207||August. 1st (Thu), 14:00||E6 Room(#1323)||Hyeok Yoon||Low-density Superconductivity in SrTiO3 Probed by Planar Tunneling Spectroscopy|
|206||Dec. 11 (Fri.), 04:00 PM||online||Hyobin Yoo(Sogang Univ.)||Atomic and electronic reconstruction at van der Waals interface in twisted 2D materials|
|205||Jun. 16 (Thu) 4PM||#1323(E6-2, 1st fl.)||Hyochul Kim, Samsung Advanced Institute of Technology||Quantum information processing using quantum dots and photonic crystal cavities|
|204||June 27 (Thu), 2:00 PM||#2502, E6-2||Hyun-Yong Lee||Gapless Kitaev Spin Liquid to Loop and String Gases|
|203||May. 8th (Wed), 16:00||E6 Room(#1323)||Jieun Lee||Imaging valley dependent electron transport in 2D semiconductors|
|202||May. 8th (Wed), 16:00||E6 Room(#1323)||Jieun Lee||Imaging valley dependent electron transport in 2D semiconductors|
|201||May. 17(Mon) 17:00||Zoom webinar||Jing Shi (UC Riverside, USA)||Spin current generation and detection in uniaxial antiferromagnets|
|200||August. 16th (Fri), 14:00||E6 Room(#1323)||Jinxing Zhang||Multiferroic and Magnetoelectric Effects by Tailoring Interfacial Chemistry and Physics in Correlated Oxides|
|199||3pm, 19th May||online||Jonghee Yoon, PhD (Assistant professor, Department of Physics, Ajou University)||(광학분야 특별세미나)Development of a multimodal optical system for improved disease diagnosis|
|198||3pm, 19th May||online||Jonghee Yoon, PhD (Assistant professor, Department of Physics, Ajou University)||(광학분야 특별세미나)Development of a multimodal optical system for improved disease diagnosis|
|197||Jan 12th (Wed), 11:00 AM||Zoom and E6 #1323||Joonseok Hur (MIT)||Spectroscopic study of trapped ions towards probing dark matter and new physics|