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장소 #1323, E6-2 
일시 June 22 (Fri.), 04:00 PM 
연사 Dr. Daniel Sando 

Physics Seminar

 

 

Tuning functional properties of BiFeO3films using strain and growth chemistry

 

Dr. Daniel Sando

Univ. of New South Wales, Sydney

 

June 22 (Fri.), 04:00 PM

#1323, E6-2

 

Abstract:

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 [1] its properties are sensitive to strain [2,3]. The discovery of the epitaxially-stabilized “super tetragonal phase” of BFO (T-BFO) [4] incited a flurry of research activity focused on understanding the phase transition and its possible functionalities [5]. T-BFO is also multiferroic, with large ferroelectric polarization and antiferromagnetic order [4], and the strain relaxation-induced T/R phase mixtures and their exceptional piezoelectric responses [6] 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 [6]. Since the oxygen configuration of the R and T polymorphs is different [5], 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 [7]. 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.

References

[1] Sando et al., J. Phys: Condens. Matt. 26, 473201 (2014). 

[2] Infante et al., PRL 105, 057601 (2010). 

[3] Sando et al., Nat. Mater. 12, 641 (2013). 

[4] Bea et al., PRL 102, 217603 (2009). 

[5] Sando et al., Appl. Phys. Rev. 3, 011106 (2016). 

[6] Zeches et al., Science 326, 977 (2009). 

[7] Sando et al., Adv. Opt Mater. 6, 1700836 (2018).

 

 

 Department of Physics, KAIST

번호 일시 장소 연사 제목
180 2009/09/07-11/30  E6, 1501  이주영박사(KIAS) 외  Physics Colloquium : 2009 Fall file
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178 2010/02/08-05/03  E6, 1501  최인수교수(서울대) 외  Physics Ciolloquium : 2010 Spring file
177 2011/09/03-12/06  E6, 1501  김용균교수(한양대) 외  Physics Colloquium : 2011 Fall file
176 2010/09/06-12/06  E6, 1501  조호진기자(조선일보) 외  Physics Colloquium : 2010 Fall file
175 2010/02/14-05/09  E6, 1501  황철주(주성엔지니어링 사장) 외  Physics Colloquium - 2011 Spring file
174 2011/05/16, 4PM  E6, 1501  서민교교수(KAIST)  Photonics with surface plasmon polaritons
173 2012/02/13-05/14  E6, 1501  Kenji Ohmori (Photo-Molecular Science, IMS)  Physics Colloquium : 2012 Spring
172 2012/04/02, 4PM  E6, 1501  Yong Hee Jeong  A new route to ferroelectricity in magnetic spinels: a case of Co2MnO4
171 2013/03/11-06/10  E6, 1501  강명수교수(KAIST) 외  Physics Colloquium : 2013 Spring
170 2013/09/09-12/09  E6, 1501  박혁규교수(부산대) 외  Physics Colloquium : 2013 Fall
169 2014/03/10-06/09  E6, 1501  신용일교수(서울대)  Physics Colloquium : 2014 Spring file
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