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
247 2016-11-18 10:30  #5318(5th fl.)  Non-equilibrium many-body spin dynamics in diamond
246 2016-10-27 16:00  #1323(E6-2)  Terahertz Metal Optics
245 2019-06-28 13:30  #1323, E6-2  Magnetic domains and domain wall conduction in pyrochlore iridate thin films and heterostructures file
244 2016-04-08 13:30  E6-2. 1st fl. #1501  Theoretical Overview of Iron-based superconductors and its future
» 2017-09-26 11:00  #1323 (E6-2. 1st fl.)  Time-resolved ARPES study of Dirac and topological materials
242 2019-11-01 14:30  E6-2. 1st fl. #1323  Squeezing the best out of 2D materials file
241 2019-04-19 14:30  E6-2. 1st fl. #1323  A family of finite-temperature electronic phase transitions in graphene multilayers file
240 2015-11-06 16:30  E6-2, #5318  Topological Dirac line nodes in centrosymmetric semimetals
239 2018-03-16 16:00  E6-2. 1st fl. #1323  Van der Waals Heterostructures from Quantum Transport to Ultrafast Optoelectronics file
238 2018-03-16 16:00  E6-2. 1st fl. #1323  Van der Waals Heterostructures from Quantum Transport to Ultrafast Optoelectronics file
237 2022-08-09 14:00  KI building (E4), Lecture Room Red (B501)  Quantum biology in fluorescent protein: a new model system to study quantum effects in biology file
236 2016-05-13 13:30  E6. #1501(1st fl.)  Aperiodic crystals in low dimensions
235 2018-04-11 16:00  #1323 (E6-2, 1st fl.)  Non-Gaussian states of multimode light generated via hybrid quantum information processing file
234 2017-05-12 13:30  E6-2. 1st fl. #1323  Topological Dirac insulator
233 2022-05-13 16:00  자연과학동(E6-2) 1st fl. #1323  High-fidelity iToffoli gate for fixed-frequency superconducting qubits file
232 2022-06-10 11:00  Online seminar  Record-quality two-dimensional electron systems file
231 2018-04-11 13:30  #1323 (E6-2, 1st fl.)  Probing 3D Structure and Physical Properties of Materials at the Single-Atom Level file
230 2018-10-15 16:00  #1323, E6-2  Universal properties of macroscopic current-carrying systems file
229 2016-09-02 16:00  E6-2(1st fl) #1323  Quantum Electrical Transport in Topological Insulator Nanowires
228 2016-09-02 14:30  E6-2(1st fl.), #1323  Nanoscale Thermal Physics: Seebeck Effect and Nanoscale Friction