visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
날짜 2017-08-31 14:00 
일시 AUG. 31 (Thu.), 2 PM 
장소 #5318(E6-2. 5th fl.) 
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)

20170831_Hiroaki Ishizuka.pdf

번호 날짜 장소 제목
280 2023-11-09 16:00  E6-2(Natural Science B/D). 1st fl. #1323  Assessing the Capability of Near-Term Photonic Devices Towards Quantum Supremacy
279 2016-09-02 14:30  E6-2(1st fl.), #1323  Nanoscale Thermal Physics: Seebeck Effect and Nanoscale Friction
278 2016-09-02 16:00  E6-2(1st fl) #1323  Quantum Electrical Transport in Topological Insulator Nanowires
277 2022-01-17 14:00  E6-2 Room 2502  Five Lectures on Observational Probes of Dark Energy file
276 2020-11-12 16:00  E6-2 1323  2020 가을학기 광학분야 특별세미나
275 2024-03-20 16:00  E6-2 #2502  [High-Energy Theory Seminar] Black hole states at finite N new
274 2024-03-13 16:00  E6-2 #2502  [High-Energy Theory Seminar] The Schwarzschild Black Hole from Perturbation Theory to all Orders
273 2022-10-26 10:00  E6-2 #2502  Replica Higher-Order Topology of Hofstadter Butterflies in Twisted Bilayer Graphene
272 2022-08-08 14:00  E6-2 #2502  Classical Shadow Tomography for Analog Quantum Simulators
271 2023-07-14 11:00  E6-2 #1501  Interfaces engineering of thin film oxides
270 2016-09-29 16:00  E6-2 #1323 (1st floor)  Large-scale Silicon Photonic MEMS Switches
269 2022-11-24 16:00  E6-2 #1323 & Zoom  Probing fundamental physics by mapping the mm and sub-mm sky
268 2023-03-16 16:00  E6-2 #1323  (광학분야 세미나) Investigation of 3D cell mechanics using refractive-index tomography
267 2023-01-09 16:00  E6-2 #1323  Non-Hermitian Hopf-bundle Matter. Moon Jip Park (IBS-PCS)
266 2023-01-10 16:00  E6-2 #1323  Terahertz Spectroscopy of Quantum Materials, Jae Hoon Kim (Yonsei University)
265 2023-03-24 11:00  E6-2 #1323  (응집물리 세미나)Floquet simulators of topological surface states in isolation
264 2022-11-03 13:00  E6-2 #1323  [High-Energy Theory Seminar] Supersymmetric observables via Fermi-gas method
263 2023-04-06 16:00  E6-2 #1323  (광학분야 세미나)Nanophotonics-based approaches to explore Berry physics
262 2024-01-24 15:00  E6-2 #1323  Determination of single molecule loading rate during mechanotransduction file
261 2023-03-30 16:00  E6-2 #1323  (광학분야 세미나)Scalable quantum entanglement in trapped-ions based quantum computer