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
574 2017-08-16 16:00  #1322 (E6-2. 1st fl.)  Phonon-driven spin-Floquet valleytro-magnetism file
573 2017-03-24 16:00  #1323 (1st fl. E6-2)  Graphene based nano electronics and nano electromechanics; focusing on precise control of nano structures for studying accurate physical properties
572 2017-03-24 14:30  #1323 (1st fl. E6-2).  Topological Dynamics
571 2017-11-03 16:00  #1323 (1st fl., E6-2.)  Expedition to the Kitaev Quantum Spin Liquid: Hunting for Majorana fermions file
570 2017-11-03 14:30  #1323 (1st fl., E6-2.)  Quantum Resistor-Capacitor Circuit with Majorana Edge States file
569 2016-06-14 15:00  #1323 (E6-2 1st fl.)  No-Insulation High Temperature Superconductor Magnet Technology for Compact, Reliable, and Low-Cost High Field DC Magnets
568 2019-10-29 10:00  #1323 (E6-2, 1st fl.)  Unconventional Spin Transport in Quantum Materials file
567 2018-04-13 10:00  #1323 (E6-2, 1st fl.)  Quantum meets Mechanics: from Quantum Information to Fundamental Research file
566 2018-04-11 16:00  #1323 (E6-2, 1st fl.)  Non-Gaussian states of multimode light generated via hybrid quantum information processing file
565 2019-10-16 16:00  #1323 (E6-2, 1st fl.)  Emergent black holes and monopoles from quantum fields file
564 2019-10-29 16:00  #1323 (E6-2, 1st fl.)  Particles and Gravity via String Geometry file
563 2019-10-31 10:00  #1323 (E6-2, 1st fl.)  Kondo meets Hubbard: Impurity physics for correlated lattices file
562 2018-04-11 13:30  #1323 (E6-2, 1st fl.)  Probing 3D Structure and Physical Properties of Materials at the Single-Atom Level file
561 2017-09-13 16:00  #1323 (E6-2. 1st fl.)  An Introduction to Quantum Spin Liquids file
560 2017-04-28 16:00  #1323 (E6-2. 1st fl.)  Carbon nanotubes coupled to superconducting impedance matching circuits
559 2017-07-14 15:00  #1323 (E6-2. 1st fl.)  Chiral anomaly in disordered Weyl semimetals file
558 2017-06-02 16:00  #1323 (E6-2. 1st fl.)  Maxwell's demon in quantum wonderland file
» 2017-09-26 11:00  #1323 (E6-2. 1st fl.)  Time-resolved ARPES study of Dirac and topological materials
556 2017-09-12 16:00  #1323 (E6-2. 1st fl.)  Exact Solution for the Interacting Kitaev Chain at Symmetric Point file
555 2017-11-28 16:00  #1323 (E6-2. 1st fl.)  Physics after the lab and the desk: Your work in PRL file