visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
날짜 2017-09-26 11:00 
일시 Sep. 26 (Tue.), 11AM 
장소 #1323 (E6-2. 1st fl.) 
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 날짜 장소 제목
공지 2022-10-24 16:00  E6 #1501(공동강의실)  Physics Colloquim(Fall 2022)
공지 2022-09-21 10:30  E6-1 #1501  [Update 세미나 영상] Distinguished Lecture 'The Magic of Moiré Quantum Matter' Prof. Pablo Jarillo-Herrero(Department of Physics, MIT)
공지 2022-11-11 11:00  E6-2 #1323  [Update 세미나영상] (응집물리 세미나) Honeycomb oxide heterostructures for quantum spin liquid
공지 2022-10-28 11:00  E6-2 #1323  [Update 세미나영상] (응집물리 세미나) Machine-Learning-Guided Prediction models and Materials discovery for high Tc cuprates
공지 2022-10-07 11:00  E6-2 #1323  [Update 세미나 영상] (응집물리 세미나) Competing orders in a vanadium-based kagome metal monolayer
공지 2022-09-23 11:00  E6-2 #1323  [Update 세미나 영상] (응집물리 세미나) Steady Floquet-Andreev states in graphene Josephson junctions
공지 2022-09-22 11:00  E6-1 #1323  2022 가을학기 응집물리 및 광학 세미나 전체 일정
434 2019-09-18 16:00  Seminar Room #1323  Fall 2019: Physics Seminar Serises file
433 2019-09-02 16:00  Seminar Room 1501  Fall 2019: Physics Colloquium file
432 2020-09-24 09:00  Zoom Video  (CAPP/IBS)Searching for Dark Matter with a Superconducting Qubit , Cryogenic Microwave Circuit Development at the NSTU file
431 2021-01-28 18:00  Online Seminar  Quantum metamaterials: concept, theory, prototypes and possible applications file
430 2015-12-09 14:00  E6-2, #1323  SWELLABLE COLLOIDAL PARTICLES ARE SWELL
429 2015-12-09 11:00  E4(KI Building), Connect room (2nd fl.)  Functional Imaging & Monitoring of Brain & Breast with Diffuse Light
428 2020-09-28 17:30  Zoom webinar  KAIST Global Forum for Spin and Beyond(Fourth Forum) file
427 2021-04-19 19:00  Zoom webinar  Evidence of Electrical Switching in Antiferromagnets and Coherent Spin Pumping file
426 2017-12-14 15:00  Seminar Room (C303), Creation Hall (3F), KAIST Munji Campus  Exploring the Universe via GWs in the era of multi-messenger astronomy
425 2019-10-25 15:00  #1323, E6-2  Physics Seminar file
424 2016-12-12 13:30  1:30p.m. #1323(E6-2. 1st fl.)  “Possible symmetry in the phase diagrams of electron- & hole-doped cuprate high-Tc superconductors”
423 2016-04-06 15:30  E6-2, RM #1323  Superconducting Quantum Interference Devices for Precision Detection
422 2016-04-05 16:00  E6-2. 1st fl. #1322  A new impurity solver for multi-orbital systems: adaptive truncation of the Hilbert space
421 2016-01-11 16:00  E6-2, #1323  Mott Physics in the Strong Spin-Orbit Coupling Regime
420 2016-11-11 16:00  #1323(E6-2. 1st fl.)  Dirac fermions in condensed matters
419 2019-06-28 14:00  E6-2, #1322  1st Research-exchange meeting of computational material physics file
418 2016-05-11 16:00  E6-2. #1323(1st fl.)  The quest for novel high-temperature superconductors---Prospects and progress in iridates
417 2018-02-12 15:00  #C303, (Creation Hall 3F, KAIST Munji Campus)  The recent result of XMASS Experiment
416 2022-09-30 16:00  E6-2. 1st fl. #1323 & Zoom  Spin-orbit torque-based spintronic devices file
415 2019-01-07 15:00  E6-2. 2st fl. #2501  Many-Body Invariants for Multipoles in Higher-Order Topological Insulators file