nonlinear optical responce from broken time reversal symmetry systems

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K04704
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Optical engineering, Photon science
• Research Institution: National Institute for Materials Science
• Principal Investigator: Inoue Jun-ichi 国立研究開発法人物質・材料研究機構, 国際ナノアーキテクトニクス研究拠点, 主幹研究員 (90323427)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 光誘起現象 / トポロジー / 量子ホール効果

Outline of Final Research Achievements

In recent extensive studies of emergent phenomena in solid-state systems, alteration of the symmetry inherent to a given system by applying an external time-dependent field is a central issue. We have found that how the time reversal symmetry is broken is not solely determined by temporal aspects, but also committed to spatial symmetry of the system. This connection between spatial and temporal symmetries induces various interesting phenomena that have not yet been discussed. This work reports one of these: symmetry-protected band sticking together in an effective- energy band structure of periodically driven electron systems. However, this, in turn, leads to another difficulty that conventional topological numbers cease to be well-defined. As such, we propose an alternative that is a natural extension of the previous one. To show validity, we confirmed firm consistency with well-established concepts.

Free Research Field

光物性理論