2016/10/03(Mon) 10:30 -11:30 五樓第一會議室 5F, 1st Meeting Room
Title
Optical excitation in magnetic topological insulators
Speaker
小川直毅 博士 (日本理化學研究所創發物性科學研究中心) Dr. Naoki Ogawa (RIKEN Center for Emergent Matter Science (CEMS), Japan)Abstract
Doping topological insulators (TIs) with magnetic elements brings about essential modifications in their originally mass-less surface states, providing a new path towards exotic physics and future applications. Examples are quantized magnetoelectric effects [1] and quantum anomalous Hall (QAH) effects [2,3], which would materialize dissipation-less electronics. However, their nonequilibrium electron/spin dynamics and finite-frequency responses at the modified Dirac states are still elusive, possibly unveiling additional functions of TIs through new experimental trials. In addition, with the progress of film fabrication techniques, including the design of superlattices and modulation dopings [4], variety of cooperative phenomena would be explored.
In this talk, we discuss several optical responses observed recently in thin films of magnetic topological insulators; (i) generation of large zero-bias photocurrent [5], and (ii) quantum Faraday and Kerr rotations [6], resulting from magnetic modifications of the Dirac states.
[1] A. M. Essin et al., Phys. Rev. Lett. 102, 146805 (2009). [2] C. Z. Chang et al., Science 340, 167 (2013). [3] J. G. Chekelsky et al., Nature Phys. 10, 731 (2014). [4] M. Mogi et al., Appl. Phys. Lett. 107, 182401 (2015). [5] N. Ogawa et al., Nature Commun. 7, 12246 (2016). [6] K. N. Okada et al., Nature Commun. 7, 12245 (2016).
Language
演講語言 (Language): in English
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