Date
March 16 at 17:00 - 18:15, 2021 (JST)
Speaker
Prof. Takahiro Morimoto (Associate Professor, Department of Applied Physics, The University of Tokyo) Edit
Venue
via Zoom
Language
English

Time: 5pm ~ 6:15pm (JST); 9am ~ 10:15am (CET)

The responses of materials to high intensity light, i.e., nonlinear optical responses, constitute a vast field of physics and engineering. While geometry and topology has been playing a central role in recent studies of condensed matters, geometrical aspects of nonlinear optical effects have not been fully explored so far. In this talk, I will show a few examples of nonlinear optical effects that have geometrical origins. First, I present that the second-order nonlinear optical effects including the shift-current, a candidate mechanism for recently discovered solar cell action in perovskite materials, has a close relationship to the modern theory of polarization, and is described by the Berry connection of Bloch wave function [1]. I will also discuss how electron correlations can enhance/modify shift current response in inversion broken materials. Next, I show that another second-order nonlinear effect, circular photogalvanic effect (CPGE), is governed by Berry curvature and shows quantization in Weyl semimetals [2]. I will report a recent measurement on chiral multifold fermion RhSi that observed a plateau structure in CPGE which is consistent with the expected quantization [3].

*Detailed information about the seminar refer to the email.

References

  1. T. Morimoto, and N. Nagaosa, Sci. Adv. 2, e1501524 (2016).
  2. F. de Juan, A. G. Grushin, T. Morimoto, and J. E. Moore, Nat. Commun. 8, 15995 (2017).
  3. D. Rees, K. Manna, B. Lu, T. Morimoto, H. Borrmann, C. Felser, J. Moore, D. Torchinsky, J. Orenstein, Sci. Adv. 6, eaba0509 (2020).

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