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 Sep.22 2022  E6-1 #1323    2022 가을학기 응집물리 및 광학 세미나 전체 일정
278 Nov. 9 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Pilkyung Moon  Moiré superlattices – from twisted bilayer graphene to quasicrystal file
277 10AM, 29th Mar. / 13:30 PM, 30th Mar.  E6 #1501/zoom, E6 #2502/zoom  Dr. RYO HANAI (APCTP)  Non-reciprocal phase transitions file
276 10AM, 31th Mar.  E6 #1501/zoom  Dr. Samuel Begg (APCTP)  Weiss fields for Quantum Spin Dynamics file
275 October 15, 5:00pm  https://bit.ly/3ndIiJn  Dr. Samuli Autti  Time crystals, quasicrystals, and time crystal dynamics in the superfluid universe file
274 Jun. 2 (Fri.), 4:00 PM  #1323 (E6-2. 1st fl.)  Dr. Sang Wook Kim  Maxwell's demon in quantum wonderland file
273 2015/12/03, 4PM  E6-2, #1323  Dr. Sang-Yun Lee (3rd institute of Physics, University of Stuttgart, Germany)  Hybrid solid state spin qubits in wide bandgap semiconductors
272 Jun. 10 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Sanghoon Kim(Department of Physics, University of Ulsan)  Fe5GeTe2의 나선형 자성특성과 자기저항의 전류밀도 의존성 연구 file
271 Mar. 24 (Fri.), 4:00 PM  #1323 (1st fl. E6-2)  Dr. SangWook Lee  Graphene based nano electronics and nano electromechanics; focusing on precise control of nano structures for studying accurate physical properties
270 Sep. 29th(Thu), 4PM  E6-2 #1323 (1st floor)  Dr. Sangyoon Han, Department of Physics, KAIST  Large-scale Silicon Photonic MEMS Switches
269 2015/07/15, 2PM  E6-2,1323  Dr. Se Young Park(Rutgers Univ.)  Electronic and optical properties of titanate-based oxide superlattices
268 June 17 (Mon.), 10:30 AM  #1323, E6-2  Dr. See-Hun Yang  Chiral Spintronics file
267 Apr. 19 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Seok Kyun Son  Graphene and hBN heterostructures file
266 2016/1/26, 2PM  E6-2, #1323  Dr. Sergei V. Kalinin (Center for Nanophase Materials Sciences, Oak Ridge National Laboratory)  Electrochemistry on Nano- and Atomic Levels: Scanning Probe Microscopy Meets Deep Data
265 Mar. 29 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Seung Hyub Baek  Epitaxial Multifunctional Oxide Thin Films for Novel Electronics file
264 Jun. 01 (Fri.), 11:00 AM  E6-2. 1st fl. #1323  Dr. Seung Sae Hong  Topological phases in low-dimensional quantum materials file
263 October 29 (Tue.), 4:00pm  #1323 (E6-2, 1st fl.)  Dr. Seung-Joo Lee  Particles and Gravity via String Geometry file
262 Apr. 09 (Mon.), 11:00 AM  E6-2. 1st fl. #1323  Dr. Seung-Sup B. Lee  Doublon-holon origin of the subpeaks at the Hubbard band edges file
261 October 31 (Thu.), 10:00am  #1323 (E6-2, 1st fl.)  Dr. Seung-Sup Lee  Kondo meets Hubbard: Impurity physics for correlated lattices file
260 Jun. 10 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Seunghun Lee(Department of Physics, Pukyong National University)  Combinatorial strategy for condensed matter physics: study on rare earth hexaborides thin films file
259 February 13th (Thur.), 16:30 PM  E6-6, #119  Dr. Seyoon Kim(University of Wisconsin-Madison)  Enhanced Light-Matter Interactions in Graphene with Noble Metal Plasmonic Structures file