visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
장소 #1323 (E6-2. 1st fl.) 
일시 Sep. 26 (Tue.), 11AM 
연사 Dr. Yukiaki Ishida / ISSP, University of Tokyo 

Time-resolved ARPES study of Dirac and topological materials

 Dr. Yukiaki Ishida / ISSP, University of Tokyo

 Sep. 26 (Tue.), 11AM

#1323 (E6-2. 1st fl.)

 

 

Time- and angle-resolved photoemission spectroscopy (TARPES) has become a powerful tool to investigate the non-equilibrated states and dynamics of matter from an electronic structural point of view. Being a surface sensitive method, TARPES has also opened pathways to explore the ultrafast phenomena occurring on the edge of matter. We present investigations done on Dirac and topological materials by using a TARPES apparatus that achieves the energy resolution of 10.5 meV and high stability [1].

       1. Classification of the topological phase of matter:

In 2008, it was demonstrated that there are two classes in non-magnetic insulators. A topological twist can be defined for the bulk band structure, and those that have the twist belong to the topologically-nontrivial class. The effect of the twist appears on the edge: On surface of topological insulators (TIs), novel Dirac-type dispersion is formed. Thus, the classification can be done by investigating whether the surface Dirac dispersion exists or not. 

2. Functioning surface of topological insulators by light:

We discovered that surface photo-voltage (SPV) can emerge on TIs when the bulk is sufficiently insulating [5]. That is, TIs now meet the well-known opto-electronic function of semiconductors. We discuss that the SPV effect can be utilized to generate spin-polarized current on TI surface, and present the ongoing research towards this end. 

3. Ultrafast dynamics of Dirac electrons:

Massless Dirac fermions have the ability to absorb light of whatever color. Thus, Dirac fermions are prospective in opto-electronics. In fact, ultrashort pulses of any color can be created by using TIs and graphitic materials. Broad-band lasing may also be realized if a population inversion can be formed across the Dirac point. Firm understanding of the Dirac electron dynamics thus becomes of paramount importance. We show that an inverted population is realized in the surface Dirac band of a TI Sb2Te3 [6]. Dynamics being either within or beyond a simple two-temperature model scheme is observed in layered Dirac semimetals such as graphite and SrMnBi2 [7].

[1] Y. Ishida et al., Rev. Sci. Instrum. 85, 123904 (2014); Y. Ishida et al., Sci. Rep. 6, 18747 (2016). 

[3] P. Zhang et al., Phys. Rev. Lett. 118, 046802 (2017). 

[3] S. Kim et al., Phys. Rev. Lett. 112, 136802 (2014). 

[4] I. Belopolski et al., Nature Commun. 7, 13643 (2016). 

[5] Y. Ishida et al., Sci. Rep. 5, 8160 (2015); M. Neupane et al., Phys. Rev. Lett. 115, 116801 (2015).

[6] S. Zhu et al., Sci. Rep. 5, 13213 (2015). 

[7] Y. Ishida et al., Sci. Rep. 1, 64 (2011); Y. Ishida et al., Phys. Rev. B 93, 100302(R) (2016). 

 

번호 일시 장소 연사 제목
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
196 May. 11 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Kun Woo Kim  Disordered Floquet topological insulators file
195 May 9 (Wed.), 04:00 PM  #1323, E6-2  Prof. Jong-Soo Rhyee  Recent advances in thermoelectric bulk composites file
194 May 9 (Thu.), 16:00 PM  #1323, E6-2  Prof. Kwang Geol Lee  Quantum Optical Sensing Using Single Photons And Single Photon Emission from Single Emitters file
193 May 9 (Thu.), 16:00 PM  #1323, E6-2  Prof. Kwang Geol Lee  Quantum Optical Sensing Using Single Photons And Single Photon Emission from Single Emitters file
192 May. 8th (Wed), 16:00  E6 Room(#1323)  Jieun Lee  Imaging valley dependent electron transport in 2D semiconductors file
191 May 311 (Thu.), 04:00 PM  #1323, E6-2  Prof. Teun-Teun Kim  Dynamic control of optical properties with gated-graphene metamaterials file
190 May 31 (Tue.) 4 PM  #1323(E6-2, 1st fl.)  Dr. Kimin Kim, KAIST  Understanding 3D tokamak physics towards advanced control of toroidal plasma
189 May 31 (Fri.), 11:00 AM  #1323, E6-2  Prof. Guido Burkard  Cavity QED with Spin Qubits file
188 May 30 (Thu.), 16:00 PM  #1323, E6-2  Prof. Chang-Hee Cho  Tuning the excitonic properties of semiconductors with light-matter interactions file
187 May 29 (Tue.), 04:00 PM  #1323, E6-2  Prof. Jae-Won Jang  Investigation on metal nanostructure/semiconductor junction and its applications file
186 May 24 (Tue) 4 PM  E6-2. #1323(1st fl.)  Dr. Euyheon Hwang, SKKU Advanced Institute of Nanotechnology, Sung Kyung Kwan University  Electronic and magnetic properties of 2D transition-metal thiophosphates and tunability of magnetic order with carrier density
185 May 24 (Fri.), 16:00 PM  #1323, E6-2  Prof. Soonjae Moon  Infrared spectroscopy study on metal-insulator transitions in layered perovskite iridates file
184 May 21 (Tue.), 4:00 PM  #5318, E6-2  임준원 박사  Classification of flat bands according to the band-crossing singularity of Bloch wave functions file
183 May 2 (Thu.), 4:00 PM  #1323, E6-2  Prof. Joon Ik Jang  Anomalous optical properties of halide perovskites file
182 May 19, 2016 (Thur.) 3PM  May 19, 2016 (Thur.) 3PM,  Dr. Michael Betz, CERN  The CERN Resonant WISP Search: Development, Results and Lesson-Learned
181 May 19 (Thu) 4PM  #1323(E6-2, 1st fl.)  Dr. Heedeuk Shin, POSTECH  Nonlinear/quantum optical effect in silicon nano-photonics
180 May 16, 2016 (Mon) 4PM  #1323(E6-2, 1st Fl.)  Dr. Daniel Bowring , Fermi National Accelerator Laboratory  Tuning microwave cavities with biased nonlinear dielectrics for axion searches
179 May 13 (Fri.), 1:30 PM  E6. #1501(1st fl.)  Dr. Young-Woo Son, Dept. of Physics, KIAS  Aperiodic crystals in low dimensions
178 May 13 (Fri.) 4 PM  E6. #1501(1st fl.)  Dr. Hosub Jin, Dept. of Physics, UNIST  Graphene analogue in (111)- BaBiO3 bilayer heterostructures for topological electronics
177 May 11 (Wed.), 4 PM  E6-2. #1323(1st fl.)  Dr. Bumjoon Kim, Max Planck Institute for Solid State Research  The quest for novel high-temperature superconductors---Prospects and progress in iridates