题目：Z₂ x Z₃ vortex in hexagonal manganites                     
报告人：Xueyun Wang（Department of Physics , University of Science and Technology Beijing）
 时间：2015年12月14日（周一）下午14：30
 地点：中科院物理研究所 M253 会议室
 摘要：
In this talk, I will introduce hexagonal REMnO₃ (RE= rare earths) with RE=Ho-Lu, Y, and Sc, which is an improper ferroelectric where the size mismatch between RE and Mn induces a trimerization-type structural phase transition, and this structural transition leads to three structural domains and two ferroelectric polarization domains, which can be viewed as topological vortices and antivortices[1]. We reported that the network of vortices can be neatly analyzed by graph theory and the evolution in the presence of electric field is related to domain preferential attachment [2, 3]. The vortices network turns out to be three-dimensional vortex loops, which result from the emergent continuous U(1) symmetry near the critical temperature [4]. This spontaneous trapping of topological defects in the process of undergoing a continuous phase transition is related with so-called Kibble-Zurek mechanism, which is proposed to test the birth of cosmos. Meanwhile, the manipulation of topological defects also will be discussed in this talk [5].
[1] Fei-Ting Huang, Xueyun Wang, Sinead Majella Griffin, Yu Kumagai, Ming-Wen Chu, Oliver Gindele, Yoichi   Horibe, Nicola Spaldin, and Sang-Wook Cheong, Phys. Rev. Lett., 113, 267602 (2014)
[2] Fei Xue, Xueyun Wang, Ion Socolenc, Yijia Gu, Long-Qing Chen and Sang-Wook Cheong Scientific Reports, 5, 17057 (2015)
[3] Xueyun Wang, Fei-Ting Huang, Rongwei Hu, Fei Fan and Sang-Wook Cheong, Invited paper in Applied Physics Letters Material, 3, 041505 (2015)
[4] Shi-Zeng Lin*, Xueyun Wang*, Yoshitomo Kamiya, Gia-Wei Chern, Fei Fan, David Fan, Brian Casas, Yue Liu, Valery Kiryukhin, Wojciech H. Zurek, Cristian D. Batista, and Sang-Wook Cheong, Nature Physics, 10, 970-977 (2014)
[5] Xueyun Wang, M. Mostovoy, M. G. Han, Y. Horibe, T. Aoki, Y. Zhu and S.-W. Cheong, Phys. Rev. Lett., 112, 247201 (2014)
简介：
Research interests:
(1) Ferroelectrics, multiferroics;
(2) Novel functional materials including oxides and intermetallics;
(3) Functional domain and domain walls;
(4) Unconventional electronic and magnetic states;
More than 300 crystals growth and crystal characterization experience (Crystal growth bygrain growth, flux, chemicalvapor transport(CVT), modified Bridgman method and floating zone(Crystal systems Corp.) ):
BaTiO₃, REMnO₃, REFeO₃ REMn₂O₅ (RE=Rare Earth), InMnO₃, In(Ga1-xMnx)O₃, In(Fe1-xMnx)O₃, (Lu1-xInx)FeO₃, Ni₃TeO₆, FeVO₄, Bi₂Se₃, Bi₂Se_3+x, Bi_2-xInxSe₃, NbSe₂,MoSe₂, WTe₂, MoTe₂, ReSe₂, Ba₃NbFe₃Si₂O₁₄, Cr(Ge,Si)Te₃, Sb₅O₇I, (Fe,Mn)₂Mo₃O₈
 
2015-now   Associate professor, Dept. of Physics, University of Science and Technology Beijing
 2010-2015  Research Assistant, Rutgers Center for Emergent Materials (RCEM)
2009-2015  Ph.D. in Physics, Rutgers, the State Univ. of New Jersey                                                           
 2005-2009  B.S. in physics, Renmin Univ. of China
联系人： 柴一晟 副研究员 （010-82649088）