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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
24 October 4 (Thu.), 16:00 PM  #1323, E6-2  Prof. Soo Jin Kim  Engineering light absorption in an ultrathin semiconductor metafilm file
23 Sep. 02(Fri) 2:30 PM  E6-2(1st fl.), #1323  Dr. Yong-Hyun Kim,Graduate School of Nanoscience and Technology, KAIST  Nanoscale Thermal Physics: Seebeck Effect and Nanoscale Friction
22 Sep. 02(Fri) 4:00 PM  E6-2(1st fl) #1323  Dr. Yong-Joo Doh, Department of Physics and Photon Science, GIST  Quantum Electrical Transport in Topological Insulator Nanowires
21 Sep. 10 (Tue.), 03:00 PM  E6-2. 1st fl. #1323  Dr. Mikhail Kiselev  Two-Stage Kondo Effect file
20 Sep. 12 (Tue.), 4 PM  #1323 (E6-2. 1st fl.)  Prof. Yi. Zhou (The Zhejiang Univ.)  Exact Solution for the Interacting Kitaev Chain at Symmetric Point file
19 Sep. 13 (Wed.), 4 PM  #1323 (E6-2. 1st fl.)  Prof. Yi. Zhou (The Zhejiang Univ.)  An Introduction to Quantum Spin Liquids file
18 Sep. 22 (Fri.), 01:00 PM  E6-2. 1st fl. #1323  Dr. EunSeong Kim / Department of Physics, KAIST  Superconductor-metal-insulator transition in thin Tantalum films file
17 Sep. 22 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. GilHo Lee / Department of Physics, POSTECH  Quantum Electronic Transport in Graphene Hybrid Nanostructures file
16 Sep. 22 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. GilHo Lee / Department of Physics, POSTECH  Unexpected Electron-Pairing in Integer Quantum Hall Effect file
15 Sep. 22, 2016(Thu), 3:30 PM  #1323(E6-2, 1st fl.)  Dr. Haiyang Yan (Institute of Nuclear Physics and Chemistry)  Polarized 3He, Polarized Neutrons and New Interactions beyond the Standard Model
14 Sep. 22, 2016(Thu), 3:30 PM  #1323(E6-2, 1st fl.)  Dr. Haiyang Yan (Institute of Nuclear Physics and Chemistry)  Polarized 3He, Polarized Neutrons and New Interactions beyond the Standard Model
» Sep. 26 (Tue.), 11AM  #1323 (E6-2. 1st fl.)  Dr. Yukiaki Ishida / ISSP, University of Tokyo  Time-resolved ARPES study of Dirac and topological materials
12 Sep. 27 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Joon Sue Lee  Spin-charge conversion in topological insulators for spintronic applications file
11 Sep. 27 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Jindong Song  0D/1D/2D/3D III-V materials grown by MBE for Optelectronics file
10 Sep. 29 (Thu), 4:00 PM  E6-2. #2501(2nd fl.)  Dr. Minu Kim, Institute for Basic Science, Seoul National University  Exploring the phase diagram of BaBiO3: epic voyage of just another bad trip?
9 Sep. 29th(Thu), 4PM  E6-2 #1323 (1st floor)  Dr. Sangyoon Han, Department of Physics, KAIST  Large-scale Silicon Photonic MEMS Switches
8 Sep. 4 (Tue), 02:30 PM  E6-2. 2st fl. #2502  Dr. Changmin Lee, MIT  Ultrafast time- and angle-resolved photoemission spectroscopy (tr-ARPES) with extreme ultraviolet laser pulses file
7 Sep10(Tue), 15:00  #2502, E6-2  Jun Ho Son  (2+1) D Duality Web from 3D Euclidean Lattice file
6 September 18(Wed.), 16:00PM  #1323, E6-2  Prof.David Schuster  Exploring Synthetic Quantum Matter in Superconducting Circuits file
5 September 20 (Thu.), 16:00  #1323, E6-2  Prof. Joo-Hiuk Son  Toward Cancer Treatment Using Terahertz Radiation: Demethylation of Cancer DNA file