88th CEMS Colloquium [Postponed]


Prof. Takashi Oka (ISSP, The University of Tokyo)


17:30 - 18:30, January 20, 2021 (Wednesday)


Okochi-Hall, RIKEN


Theory of laser-induced chiral effects in Dirac semimetals


Geometric effects and topology have now become a standard and essential concept in understanding quantum materials in equilibrium. Recently, many researchers are exploring their role in nonequilibrium physics. One platform to study them is the coherent dynamics of Dirac semimetals induced by intense laser fields. They provide simple but rich examples that can be probed by techniques such as higher harmonic generation [1]. We have studied 3D Dirac systems in circularly polarized laser from viewpoints such as (1) Floquet engineering of the bands [2,3], (2) topological crossover in the carrier dynamics [4], (3) geometric effects in the tunnel creation of carriers [5] and (4) nonequilibrium phase diagram in the strong coupling limit [6]. In each of these analyses, we find new mechanisms of breaking the chiral symmetry dynamically.

[1] S. Kovalev, et al. Nature communications 11, 1 (2020).
[2] TO, S. Kitamura, Annual Review of Condensed Matter Physics 10, 387 (2019).
[3] S. Ebihara, K. Fukushima, TO, Physical Review B 93, 155107 (2016).
[4] R. Dantas, Z. Wang, P. Surówka, TO, arXiv:2008.04331.
[5] S. Takayoshi, J. Wu, TO, arXiv:2005.01755.
[6] K. Hashimoto, S. Kinoshita, K. Murata, TO, JHEP, 127 (2017), S. Kinoshita, K. Murata, TO, JHEP, 96 (2018).