“Berry phase and nonlinear response: photocurrent in noncentrosymmetric insulators and Weyl semimetals”
2017.08.31 11:52
장소 | #5318(E6-2. 5th fl.) |
---|---|
일시 | AUG. 31 (Thu.), 2 PM |
연사 | Prof. Hiroaki Ishizuka (The University of Tokyo) |
“Berry phase and nonlinear response: photocurrent in noncentrosymmetric insulators and Weyl semimetals”
Prof. Hiroaki Ishizuka (The University of Tokyo)
AUG. 31 (Thu.), 2 PM / #5318(E6-2. 5th fl.)
Berry phase is one of the important keywords to understand non-trivial quantum effects. In condensed matter physics, the Berry phase often shows up in transport phenomena (e.g., quantum and anomalous Hall effects) and is considered as a keyword to understand topological properties of non-interacting fermion systems. While most of such studies have focused on the equilibrium states or linear responses in close to the equilibrium, a recent study on the photogalvanic effects have pointed out the relation between the Berry phase and photogalvanic effects in noncentrosymmetric insulators where inter-band transitions take an essential role [1-3]; it is named shift current as it is related to the shift of the Wannier function. So far, however, no observable consequences that distinguish this phenomenon from the conventional mechanism is known. In this talk, we theoretically explored the basic properties of shift current focusing on the distinction between the conventional and shift current mechanisms.
To theoretically study the photocurrent, we employed a Keldysh Green’s function formalism combined with Floquet theory. Using a large size numerical calculation, we study how the photocurrent changes by the local excitation, i.e., when only a part of the system is irradiated by the light. We show that, for the shift current, the magnitude of the current does not depend on the position of the light [4]. This is in contrast to the conventional mechanism, where the photocurrent is expected to be larger at the edge of the sample while it is suppressed when the light is at the center. Such behavior is consistent with the photocurrent recently observed in a noncentrosymmetric organic solid [5].
In the latter half of the talk, we discuss the effect of Berry phase on the photocurrent in Weyl semimetals [6,7]. We show that the Berry phase associated with the Weyl nodes induce a similar phenomenon to the adiabatic pump, resulting in a dissipation-less photocurrent. We find that the photocurrent appears only with the circularly polarized lights. This mechanism may potentially explain the photocurrent observed in TaAs [8].
[1] W. Kraut and R. von Blatz, Phys. Rev. B 19, 1548 (1979); ibid. 23, 5590 (1981).
[2] J. E. Sipe and A. I. Shkrebtii, Phys. Rev. B 61, 5337 (2000).
[3] T. Morimoto and N. Nagaosa, Science Adv. 2, e1501524 (2016).
[4] H. Ishizuka and N. Nagaosa, New J. Phys. 19, 033015 (2017).
[5] M. Nakamura, et al., Nature Commun. 8, 281 (2017).
[6] H. Ishizuka et al., Phys. Rev. Lett. 117, 216601 (2016).
[7] H. Ishizuka et al., Phys. Rev. B 95, 245211 (2017).
[8] Q. Ma et al., preprint (arXiv: 1705.00690).
Contact: Eun Gook Moon, Physics Dept., (egmoon@kaist.ac.kr)
댓글 0
번호 | 일시 | 장소 | 연사 | 제목 |
---|---|---|---|---|
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 |
230 | May. 12 (Fri.), 01:30 PM | E6-2. 1st fl. #1323 | Dr. Young Kuk Kim | Topological Dirac insulator |
229 | May. 11 (Fri.), 04:00 PM | E6-2. 1st fl. #1323 | Dr. Nam Kim |
암페어 단위 재정의와 단전자 펌프 소자 개발
![]() |
228 | May. 11 (Fri.), 02:30 PM | E6-2. 1st fl. #1323 | Dr. Kun Woo Kim |
Disordered Floquet topological insulators
![]() |
227 | May 9 (Wed.), 04:00 PM | #1323, E6-2 | Prof. Jong-Soo Rhyee |
Recent advances in thermoelectric bulk composites
![]() |
226 | 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
![]() |
225 | 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
![]() |
224 | May. 8th (Wed), 16:00 | E6 Room(#1323) | Jieun Lee |
Imaging valley dependent electron transport in 2D semiconductors
![]() |
223 | May 311 (Thu.), 04:00 PM | #1323, E6-2 | Prof. Teun-Teun Kim |
Dynamic control of optical properties with gated-graphene metamaterials
![]() |
222 | May 31 (Tue.) 4 PM | #1323(E6-2, 1st fl.) | Dr. Kimin Kim, KAIST | Understanding 3D tokamak physics towards advanced control of toroidal plasma |
221 | May 31 (Fri.), 11:00 AM | #1323, E6-2 | Prof. Guido Burkard |
Cavity QED with Spin Qubits
![]() |
220 | May 30 (Thu.), 16:00 PM | #1323, E6-2 | Prof. Chang-Hee Cho |
Tuning the excitonic properties of semiconductors with light-matter interactions
![]() |
219 | May 29 (Tue.), 04:00 PM | #1323, E6-2 | Prof. Jae-Won Jang |
Investigation on metal nanostructure/semiconductor junction and its applications
![]() |
218 | 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 |
217 | May 24 (Fri.), 16:00 PM | #1323, E6-2 | Prof. Soonjae Moon |
Infrared spectroscopy study on metal-insulator transitions in layered perovskite iridates
![]() |
216 | 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
![]() |
215 | May 2 (Thu.), 4:00 PM | #1323, E6-2 | Prof. Joon Ik Jang |
Anomalous optical properties of halide perovskites
![]() |
214 | May 19, 2016 (Thur.) 3PM | May 19, 2016 (Thur.) 3PM, | Dr. Michael Betz, CERN | The CERN Resonant WISP Search: Development, Results and Lesson-Learned |
213 | May 19 (Thu) 4PM | #1323(E6-2, 1st fl.) | Dr. Heedeuk Shin, POSTECH | Nonlinear/quantum optical effect in silicon nano-photonics |
212 | 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 |
211 | May 13 (Fri.), 1:30 PM | E6. #1501(1st fl.) | Dr. Young-Woo Son, Dept. of Physics, KIAS | Aperiodic crystals in low dimensions |