|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. 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 . 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 . Dynamics being either within or beyond a simple two-temperature model scheme is observed in layered Dirac semimetals such as graphite and SrMnBi2 .
 Y. Ishida et al., Rev. Sci. Instrum. 85, 123904 (2014); Y. Ishida et al., Sci. Rep. 6, 18747 (2016).
 P. Zhang et al., Phys. Rev. Lett. 118, 046802 (2017).
 S. Kim et al., Phys. Rev. Lett. 112, 136802 (2014).
 I. Belopolski et al., Nature Commun. 7, 13643 (2016).
 Y. Ishida et al., Sci. Rep. 5, 8160 (2015); M. Neupane et al., Phys. Rev. Lett. 115, 116801 (2015).
 S. Zhu et al., Sci. Rep. 5, 13213 (2015).
 Y. Ishida et al., Sci. Rep. 1, 64 (2011); Y. Ishida et al., Phys. Rev. B 93, 100302(R) (2016).
|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|
|116||Jun. 2 (Fri.), 4:00 PM||#1323 (E6-2. 1st fl.)||Dr. Sang Wook Kim||Maxwell's demon in quantum wonderland|
|115||Nov. 9 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. Pilkyung Moon||Moiré superlattices – from twisted bilayer graphene to quasicrystal|
|114||2015/10/16, 3PM||E6-2, 5th fl. #5318||Dr. Pierre Pugnat , (CNRS-LNCMI)||High Magnetic Fields to Probe the sub-eV range of Particle/Astroparticle Physics - From the OSQAR experiments at CERN up to new perspectives at LNCMI-Grenoble|
|113||July 2. 2018 (Monday) 3:00 PM||Seminar Room (C303), Creation Hall (3F), KAIST Munji Campus||Dr. Peter Winter (Argonne National Laboratory)||High Precision Magnetic Field Measurement for the Muon g-2 Experiment|
|112||Jun. 1(Wed) 10:30 AM||BK21 Conference Room (#1318, E6-2)||Dr. Noriaki Horiuchi, Editor, Nature Photonics||Welcome to Nature Photonics|
|111||May. 11 (Fri.), 04:00 PM||E6-2. 1st fl. #1323||Dr. Nam Kim||암페어 단위 재정의와 단전자 펌프 소자 개발|
|110||April 26 (Tue), 4PM||#1323(1st Floor. E6-2)||Dr. Myung-Ho Bae, Korea Research Institute of Standards and Science||Transport spectroscopy for electronic bands in carbon-based nanomaterials with weak-bond contacts|
|109||3 PM, 12 Jun (Wed), 2019||Rm# 1323, E6-2||Dr. Minyoung You||The relation between free and interacting fermionic SPT phases|
|108||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?|
|107||Apr. 28 (Fri.), 04:00 PM||#1323 (E6-2. 1st fl.)||Dr. Minkyung Jung Research Institute, DGIST||Carbon nanotubes coupled to superconducting impedance matching circuits|
|106||July 30 (Tue), 4:00 PM||#1323, E6-2||Dr. Mingu Kang||Dirac fermions and flat bands in correlated kagome metals|
|105||Nov. 3 (Fri.), 2:30 PM||#1323 (1st fl., E6-2.)||Dr. MinChul Lee(Department of Applied Physics, Kyung Hee Univ.)||Quantum Resistor-Capacitor Circuit with Majorana Edge States|
|104||Sep. 10 (Tue.), 03:00 PM||E6-2. 1st fl. #1323||Dr. Mikhail Kiselev||Two-Stage Kondo Effect|
|103||Feb. 1 (Wed.), 2p.m.||#1323(E6-2. 1st fl.)||Dr. Michihisa Yamamoto, Department of Applied Physics, The University of Tokyo||Quantum electron optics using flying electrons|
|102||2015/11/23, 1:30PM||E6-2, #1323||Dr. Michael Park (Stanford University)||What's Beyond the Standard Model? Lessons from Run I and what might come in Run II|
|101||Jul. 08 (Fri.) 11:00 AM||#1323(E6-2. 1st fl.)||Dr. Michael Lawler(Binghampton Univ. / Cornell Univ.)||Isostatic magnetism|
|100||May 19, 2016 (Thur.) 3PM||May 19, 2016 (Thur.) 3PM,||Dr. Michael Betz, CERN||The CERN Resonant WISP Search: Development, Results and Lesson-Learned|
|99||2015/10/15, 10AM||E6-2, 5th fl. #5318||Dr. Mark D. Bird (Florida State University)||Development of Large-Bore, High Field Magnets at the NHMFL|
|98||Mar. 24 (Fri.), 2:30 PM||#1323 (1st fl. E6-2).||Dr. MahnSoo Choi||Topological Dynamics|
|97||October 26 (Fri.), 4:00 PM||#1323, E6-2||Dr. Kyusung Hwang||Coexisting triple-point and nodal-line topological magnons and thermal Hall effect in pyrochlore iridates|