• 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
235 June 4 (Tue.), 5:00 PM  #1323, E6-2  Prof. Minsu Kim  Stochastic nature of bacterial eradication using antibiotics file
234 May 30 (Thu.), 16:00 PM  #1323, E6-2  Prof. Chang-Hee Cho  Tuning the excitonic properties of semiconductors with light-matter interactions file
233 May 24 (Fri.), 16:00 PM  #1323, E6-2  Prof. Soonjae Moon  Infrared spectroscopy study on metal-insulator transitions in layered perovskite iridates file
232 May 31 (Fri.), 11:00 AM  #1323, E6-2  Prof. Guido Burkard  Cavity QED with Spin Qubits file
231 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
230 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
229 May. 8th (Wed), 16:00  E6 Room(#1323)  Jieun Lee  Imaging valley dependent electron transport in 2D semiconductors file
228 May 2 (Thu.), 4:00 PM  #1323, E6-2  Prof. Joon Ik Jang  Anomalous optical properties of halide perovskites file
227 May. 3 (Fri), 11:00 AM  E6-2. 2st fl. #2502  Prof. Changhee Sohn  Exotic Magnetism file
226 May 1 (Wed), 4:00 PM  #1323, E6-2  Dr. Sungkyun Choi  Raman and x-ray scattering study on correlated electron systems: two case examples file
225 April 26 (Fri.), 4:00 PM  #1323, E6-2  Dr. Soonwon Choi  Robust Quantum Metrology using Strongly Interacting Spin Ensembles and Quantum Convolutional Neural Network file
224 April 23 (Tue.), 4:00 PM  #1323, E6-2  Prof. Johan Chang  From Mott physics to high-temperature superconductivity file
223 Apr. 19 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. YoungWoo Nam  A family of finite-temperature electronic phase transitions in graphene multilayers file
222 Apr. 19 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Seok Kyun Son  Graphene and hBN heterostructures file
221 Apr.19 (Fri.), 11:00 AM  #1323, E6-2  Dr. Ji-Sang Park  First-principles studies of semiconductors for solar cell applications file
220 April 11 (Thu.), 16:00 PM  #1323, E6-2  Prof. Joo-Hyoung Lee, GIST  Massive screening for cathode active materials using deep neural network file
219 April 4 (Thu.), 16:00 PM  #1323, E6-2  Prof. Su-Hyun Gong  Chiral spin-photon interaction at nanoscale file
218 Mar. 29 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Taeyoung Choi  Coherent Quantum Control and Magnetism on atoms – Trapped ion and ESR STM file
217 Mar. 29 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Seung Hyub Baek  Epitaxial Multifunctional Oxide Thin Films for Novel Electronics file
216 MAR. 26 (TUE), 0300 PM  E6-2. 2st fl. #2501  Prof. Jung Hoon Han  Consideration of thermal Hall effect in frustrated and un-frustrated quantum magnets file