|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|
|213||Oct. 18 (Tue.), 1:30 PM||1st fl. #1323(E6-2)||Dr. Chan-Ho Yang, Department of Physics, KAIST||"Visualization of oxygen vacancy in motion and the interplay with electronic conduction"|
|212||July 10 (Wed.), 04:00 PM-||Academic Cltural Complex (E9) 5층 스카이라운지||Prof. Sidney Nagel/Young-Kee Kim||Public Lectures|
|211||2015/08/04, 11PM||B501, Room Red, KI bldg. 5nd fl.||Dr. Eric Jin Ser Lee(Univ. of Manitoba, Canada)||Propagation of ultrasound through two- and three-dimensional strongly scattering media|
|210||Jun. 1(Wed) 10:30 AM||BK21 Conference Room (#1318, E6-2)||Dr. Noriaki Horiuchi, Editor, Nature Photonics||Welcome to Nature Photonics|
|209||October 15, 2020 (Thursday||CAPP Seminar Room #C303, Creation Hall (3F), KAIST Munji Campus||Prof. Gil-Ho Lee (POSTECH)||Graphene-based Josephson junction microwave bolometer|
|208||2015/03/13, 2PM||Connect Room, KI Bldg.||The 15th Innovative Workshop on Soft/Bio Materials|
|207||2015/12/09, 11AM||E4(KI Building), Connect room (2nd fl.)||Arjun G. Yodh (University of Pennsylvania)||Functional Imaging & Monitoring of Brain & Breast with Diffuse Light|
|206||2015/12/17, 11:00AM||E4(KI Building), Matrix Hall (2nd fl.)||Dr. Jung-Hoon Park (Purdue University)||Wavefront engineering for in-vivo Deep brain imaging|
|205||2015/07/23,1:30PM||E4, B401||Prof. Gilles Lérondel (Univ. of Technology of Troyes)||Enhanced ZnO based UV photonics and related applications|
|204||August. 16th (Fri), 14:00||E6 Room(#1323)||Jinxing Zhang||Multiferroic and Magnetoelectric Effects by Tailoring Interfacial Chemistry and Physics in Correlated Oxides|
|203||August. 6th (TUE), 14:00||E6 Room(#1323)||Kanghyun Chu||Visualization of in-plane piezoresponse vector fields|
|202||August. 1st (Thu), 14:00||E6 Room(#1323)||Hyeok Yoon||Low-density Superconductivity in SrTiO3 Probed by Planar Tunneling Spectroscopy|
|201||May. 8th (Wed), 16:00||E6 Room(#1323)||Jieun Lee||Imaging valley dependent electron transport in 2D semiconductors|
|200||Nov. 22th (Thur), 15:00||E6 Room(#1323)||Prof. Suprijadi Haryono||Experimental and Computational Study on Physical Properties based on Granular System|
|199||July 8(Mon), 14:00||E6, #1322||T. L. M. Guedes (Univ. of Konstanz)||Ultrabroadband squeezed pulses and their relation to relativity|
|198||2015/10/23-12/4 10:30 AM||E6, #1501||Prof. YongKeun Park & Prof. Tae-Young Yoon||How to write a good scientific paper[Open lecture series]|
|197||2016/03/07-06/13||E6, 1501||Prof. David Helfman(KAIST) 외||Physics Colloquium : 2016 Spring|
|196||2015/09/07-12/01||E6, 1501||문은국 교수(KAIST) 외||Physics Colloquium : 2015 Fall|
|195||2009/02/23-05/04||E6, 1501||안종현교수(성균관대) 외||Physics Colloquium : 2009 Spring|
|194||2009/09/07-11/30||E6, 1501||이주영박사(KIAS) 외||Physics Colloquium : 2009 Fall|