Discoveries of topological materials, such as topological insulators, Dirac, and Weyl semimetals, have revolutionized contemporary physics. Moreover, these materials offer exciting opportunities for upcoming quantum technologies and opto-electronics. In this talk, I will show how intense laser-driven electron dynamics in a Weyl semimetal have many intriguing features. The first interesting observation will be discussed that the parity and magnitude of the non-trivial Berry curvature’s components control the direction and strength of the anomalous current, which leads to the generation of anomalous odd-order harmonics [1,2].
In the later part, I will emphasize the generation and tailoring of photocurrent in Weyl semimetals. It is well-known that circularly polarized light fails to generate photocurrent in inversion-symmetric Weyl semimetals with degenerate Weyl nodes. While each node generates a current with a direction depending on its chirality, the two currents in the two degenerate nodes of opposite chirality cancel each other. By extension, it is also generally expected that the currents generated at the same Weyl node by the fields of opposite helicity should also observe mirror symmetry and cancel. Surprisingly, this is not the case. The origin of this effect lies in the nonlinear energy dispersion, which manifests strongly already remarkably close to the Weyl nodes, where linear dispersion is expected to hold, and the Weyl fermions are thus expected to be massless [3]. As an application of this phenomenon, we introduce a method to generate helicity-sensitive photocurrent in Weyl semimetals with degenerate Weyl nodes at the Fermi level [3-5].
References
[1] A. Bharti, M. S. Mrudul and G. Dixit, Phys. Rev. B 105, 155140 (2022).
[2] A. Bharti and G. Dixit, Phys. Rev. B 107, 224308 (2023).
[3] A. Bharti, M. Ivanov and G. Dixit, Phys. Rev. B 108, L020305 (2023).
[4] A. Bharti and G. Dixit, Phys. Rev. B 108, L161113 (2023).
[5] A. Bharti and G. Dixit, Phys. Rev. B 109, 104309 (2024).
Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076,