|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||2019/03/21 - 5/30||Seminar Room #1323||Dr. Hyangtag Lim (KIST) and etc.||Spring 2019: Physics Seminar Serises|
|공지||2019/02/25 - 06/03||Seminar Room 1501||양용수 교수 (Prof. Yongsoo Yang, KAIST) and etc.||Spring 2019: Physics Colloquium|
|40||Apr. 19(Tue.), 2PM||#1323(E6-2. 1st fl.)||Prof. Mark Koepke, Department of Physics and Astronomy, West Virginia University, USA||Nonlocal collisional electron transport in partially ionized plasma generation, structure, and stability|
|39||Jul. 08 (Fri.) 11:00 AM||#1323(E6-2. 1st fl.)||Dr. Michael Lawler(Binghampton Univ. / Cornell Univ.)||Isostatic magnetism|
|38||Jul. 07 (Thu.) 2PM||#1323(E6-2. 1st fl.)||Dr. Eun Ah Kim, CORNELL UNIV.||Let there be topological superconductors|
|37||Jul. 08 (Fri.) 2PM||#1323(E6-2. 1st fl.)||Dr. Junhyun Lee, Harvard University||Electronic quasiparticles in the quantum dimer model|
|36||Jul. 28 (Thu.) 4PM||#1323(E6-2. 1st fl.)||Prof. Johannes Pollanen, Jerry Cowen Chair of Experimental Physics at Michigan State University||Low Dimensional Electrons: On the Road to Hybrid Quantum Systems|
|35||Nov. 11th(Fri), 1:30 p.m.||#1323(E6-2. 1st fl.)||Dr. Keun Su Kim, POSTECH||Bandgap Engineering of Black Phosphorus|
|34||Nov. 11th (Fri), 4 p.m.||#1323(E6-2. 1st fl.)||Dr. Bohm-Jung Yang, SNU||Dirac fermions in condensed matters|
|33||Nov. 16 (Wed), 4p.m.||#1323(E6-2. 1st fl.)||Dr. Heung-Sik Kim , University of Toronto||Realizing Haldane Model in Fe-based Honeycomb Ferromagnetic Insulators|
|32||Nov. 24(Thu) 4p.m.||#1323(E6-2. 1st fl.)||Dr. Jai-Min Choi, Chonbuk National Univiersity||Harmonic oscillator physics with single atoms in a state-selective optical potential|
|31||Nov. 29(Tue) 4p.m.||#1323(E6-2. 1st fl.)||Dr. SungBin Lee, KAIST||Symmetry Protected Kondo Metals and Their Phase Transitions|
|30||Dec. 8(Thu) 4p.m.||#1323(E6-2. 1st fl.)||Dr. Jinhyoung Lee, Hanyang University||Dynamical Resonance between Two Optical Cavities via Optomechanical Oscillator|
|29||Dec. 9(Fri), 1:30 p.m.||#1323(E6-2. 1st fl.)||Dr. Jae Yoon Cho, POSTECH||Entanglement area law in strongly-correlated systems|
|28||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|
|27||Dec. 9(Fri), 4p.m.||#1323(E6-2. 1st fl.||Dr. Kun Woo Kim, KIAS||Shift Charge and Spin Photocurrents in Dirac Surface States of Topological Insulator|
|26||May 16, 2016 (Mon) 4PM||#1323(E6-2, 1st Fl.)||Dr. Daniel Bowring , Fermi National Accelerator Laboratory||Tuning microwave cavities with biased nonlinear dielectrics for axion searches|
|25||May 19 (Thu) 4PM||#1323(E6-2, 1st fl.)||Dr. Heedeuk Shin, POSTECH||Nonlinear/quantum optical effect in silicon nano-photonics|
|24||May 31 (Tue.) 4 PM||#1323(E6-2, 1st fl.)||Dr. Kimin Kim, KAIST||Understanding 3D tokamak physics towards advanced control of toroidal plasma|
|23||Jun. 16 (Thu) 4PM||#1323(E6-2, 1st fl.)||Hyochul Kim, Samsung Advanced Institute of Technology||Quantum information processing using quantum dots and photonic crystal cavities|
|22||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|
|21||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|