|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|
|100||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|
|99||May 19 (Thu) 4PM||#1323(E6-2, 1st fl.)||Dr. Heedeuk Shin, POSTECH||Nonlinear/quantum optical effect in silicon nano-photonics|
|98||May 19, 2016 (Thur.) 3PM||May 19, 2016 (Thur.) 3PM,||Dr. Michael Betz, CERN||The CERN Resonant WISP Search: Development, Results and Lesson-Learned|
|97||May 2 (Thu.), 4:00 PM||#1323, E6-2||Prof. Joon Ik Jang||Anomalous optical properties of halide perovskites|
|96||May 21 (Tue.), 4:00 PM||#5318, E6-2||임준원 박사||Classification of flat bands according to the band-crossing singularity of Bloch wave functions|
|95||May 24 (Fri.), 16:00 PM||#1323, E6-2||Prof. Soonjae Moon||Infrared spectroscopy study on metal-insulator transitions in layered perovskite iridates|
|94||May 24 (Tue) 4 PM||E6-2. #1323(1st fl.)||Dr. Euyheon Hwang, SKKU Advanced Institute of Nanotechnology, Sung Kyung Kwan University||Electronic and magnetic properties of 2D transition-metal thiophosphates and tunability of magnetic order with carrier density|
|93||May 29 (Tue.), 04:00 PM||#1323, E6-2||Prof. Jae-Won Jang||Investigation on metal nanostructure/semiconductor junction and its applications|
|92||May 30 (Thu.), 16:00 PM||#1323, E6-2||Prof. Chang-Hee Cho||Tuning the excitonic properties of semiconductors with light-matter interactions|
|91||May 31 (Fri.), 11:00 AM||#1323, E6-2||Prof. Guido Burkard||Cavity QED with Spin Qubits|
|90||May 31 (Tue.) 4 PM||#1323(E6-2, 1st fl.)||Dr. Kimin Kim, KAIST||Understanding 3D tokamak physics towards advanced control of toroidal plasma|
|89||May 311 (Thu.), 04:00 PM||#1323, E6-2||Prof. Teun-Teun Kim||Dynamic control of optical properties with gated-graphene metamaterials|
|88||May. 8th (Wed), 16:00||E6 Room(#1323)||Jieun Lee||Imaging valley dependent electron transport in 2D semiconductors|
|87||May 9 (Thu.), 16:00 PM||#1323, E6-2||Prof. Kwang Geol Lee||Quantum Optical Sensing Using Single Photons And Single Photon Emission from Single Emitters|
|86||May 9 (Thu.), 16:00 PM||#1323, E6-2||Prof. Kwang Geol Lee||Quantum Optical Sensing Using Single Photons And Single Photon Emission from Single Emitters|
|85||May 9 (Wed.), 04:00 PM||#1323, E6-2||Prof. Jong-Soo Rhyee||Recent advances in thermoelectric bulk composites|
|84||May. 11 (Fri.), 02:30 PM||E6-2. 1st fl. #1323||Dr. Kun Woo Kim||Disordered Floquet topological insulators|
|83||May. 11 (Fri.), 04:00 PM||E6-2. 1st fl. #1323||Dr. Nam Kim||암페어 단위 재정의와 단전자 펌프 소자 개발|
|82||May. 12 (Fri.), 01:30 PM||E6-2. 1st fl. #1323||Dr. Young Kuk Kim||Topological Dirac insulator|
|81||May. 17 (Thu.), 01:30 PM||E6-2. 1st fl. #1323||Prof. Yong-Baek Kim University of Toronto||Quantum Spin Liquid in Kitaev Materials|