Theoretical study on the nonlinear electromagnetic response in noncentrosymmetric systems

2017 Fiscal Year Final Research Report

• Project/Area Number: 16H06717
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Single-year Grants
• Research Field: Condensed matter physics II
• Research Institution: The University of Tokyo
• Principal Investigator: Ishizuka Hiroaki 東京大学, 大学院工学系研究科(工学部), 助教 (00786014)
• Project Period (FY): 2016-08-26 – 2018-03-31
• Keywords: シフト電流 / Berry位相 / ワイル半金属 / 二次高調波発生

Outline of Final Research Achievements

Photogalvanic effect and second-harmonic generation in non-centrosymmetric materials are theoretically studied in a wide range of materials from zero-gap semiconductors (Weyl semimetals) to non-centrosymmetric insulators. In zero-gap semiconductors, we find a new mechanism that contributes to the photogalvanic effect and second-harmonic generation that appears only in the zero-gap semiconductors. In the insulators, we studied the light-position dependence of the locally-excited photocurrent using an unbiased non-equilibrium Green function method. We find that the magnitude of photocurrent induced in the non-centrosymmetric systems does not depend on the position of the light, in contrast to what is generally expected in the conventional mechanism. These results potentially contribute to experimental studies on the photogalvanic effects in topological materials, which is an emerging topic in the condensed matter physics.

Free Research Field

物性理論