visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
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)

20170831_Hiroaki Ishizuka.pdf

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
144 Apr. 08 (Fri.), 13:30 PM  E6-2. 1st fl. #1501  Dr. Yunkyu Bang, Chonnam National Univ.  Theoretical Overview of Iron-based superconductors and its future
143 June 28 (Fri.), 13:30 PM  #1323, E6-2  Dr. Yusuke Kozuka  Magnetic domains and domain wall conduction in pyrochlore iridate thin films and heterostructures file
142 Oct. 27th(Thu) 4PM  #1323(E6-2)  Dr. 이 강 희, KAIST, Mechnical Engineering  Terahertz Metal Optics
141 Nov. 18th (Fri) 10:30 a.m.  #5318(5th fl.)  Dr. 최 순 원, Havard University  Non-equilibrium many-body spin dynamics in diamond
140 December 27(Fri.), 15:00  E6-2,#5318  Han Gyeol Suh  The superconducting order parameter puzzle of Sr2RuO4 file
139 Dec 27 (Fri), 3:00 PM  #5318, E6-2  Han Gyeol Suh  The superconducting order parameter puzzle of Sr2RuO4 file
138 September 26 (Thu.), 16:00 PM  #1323, E6-2  Han Seb Moon  Entanglement Swapping with Autonomous Polarization-Entangled Photon-Pairs from Warm Atomic Ensemble file
137 January 17 (Fri), 4:00 PM  #1323, E6-2  Hiroki Ikegami  Symmetry Breaking and Topology in Superfluid 3He file
136 August 27 (Tue.), 4:00PM  Rm. 1323, E6  Hiroshi Eisaki  Critical current properties of Fe-based superconductors file
135 August. 1st (Thu), 14:00  E6 Room(#1323)  Hyeok Yoon  Low-density Superconductivity in SrTiO3 Probed by Planar Tunneling Spectroscopy file
134 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
133 June 27 (Thu), 2:00 PM  #2502, E6-2  Hyun-Yong Lee  Gapless Kitaev Spin Liquid to Loop and String Gases file
132 May. 8th (Wed), 16:00  E6 Room(#1323)  Jieun Lee  Imaging valley dependent electron transport in 2D semiconductors file
131 May. 8th (Wed), 16:00  E6 Room(#1323)  Jieun Lee  Imaging valley dependent electron transport in 2D semiconductors file
130 August. 16th (Fri), 14:00  E6 Room(#1323)  Jinxing Zhang  Multiferroic and Magnetoelectric Effects by Tailoring Interfacial Chemistry and Physics in Correlated Oxides file
129 Sep10(Tue), 15:00  #2502, E6-2  Jun Ho Son  (2+1) D Duality Web from 3D Euclidean Lattice file
128 July 21 - August 2  E6-2,# 5318  Junmou Chen/Thomas Flacke/Kaoru Hagiwara/Junichi Kanzaki/Chris Kelso/Jeong Han Kim/Kyoungchul Kong/Gabriel Lee/Hye-Sung Lee/Ian Lewis  Challenges and Opportunities in Theoretical Particle Physics 2019 file
127 August. 6th (TUE), 14:00  E6 Room(#1323)  Kanghyun Chu  Visualization of in-plane piezoresponse vector fields file
126 2012/02/13-05/14  E6, 1501  Kenji Ohmori (Photo-Molecular Science, IMS)  Physics Colloquium : 2012 Spring
125 Jun 1 (Wed) 4 PM  #1323(E6-2 1st fl.)  Kil-Byoung Chai, Caltech  Laboratory experiments relevant to mesospheric clouds, Saturn’s rings & astrophysical jets