Light-Driven Extremely Nonlinear Bulk Photogalvanic Currents

Open Access

Light-Driven Extremely Nonlinear Bulk Photogalvanic Currents

Ofer Neufeld, Nicolas Tancogne-Dejean, Umberto De Giovannini, Hannes Hübener, and Angel Rubio

Phys. Rev. Lett. 127, 126601 – Published 13 September 2021

Abstract

We predict the generation of bulk photocurrents in materials driven by bichromatic fields that are circularly polarized and corotating. The nonlinear photocurrents have a fully controllable directionality and amplitude without requiring carrier-envelope-phase stabilization or few-cycle pulses, and can be generated with photon energies much smaller than the band gap (reducing heating in the photoconversion process). We demonstrate with ab initio calculations that the photocurrent generation mechanism is universal and arises in gaped materials (Si, diamond, MgO, hBN), in semimetals (graphene), and in two- and three-dimensional systems. Photocurrents are shown to rely on sub-laser-cycle asymmetries in the nonlinear response that build-up coherently from cycle to cycle as the conduction band is populated. Importantly, the photocurrents are always transverse to the major axis of the co-circular lasers regardless of the material’s structure and orientation (analogously to a Hall current), which we find originates from a generalized time-reversal symmetry in the driven system. At high laser powers ( $\sim 10^{13} W / {cm}^{2}$ ) this symmetry can be spontaneously broken by vast electronic excitations, which is accompanied by an onset of carrier-envelope-phase sensitivity and ultrafast many-body effects. Our results are directly applicable for efficient light-driven control of electronics, and for enhancing sub-band-gap bulk photogalvanic effects.

Received 2 May 2021
Accepted 28 July 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.126601

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Open access publication funded by the Max Planck Society.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Nonlinear optics Photogalvanic effect Ultrafast phenomena

First-principles calculations Time-dependent DFT

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Ofer Neufeld ^1,*, Nicolas Tancogne-Dejean ¹, Umberto De Giovannini ^1,2,4, Hannes Hübener ¹, and Angel Rubio ^1,3,4,†

¹Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Hamburg 22761, Germany
²IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain
³Center for Computational Quantum Physics (CCQ), The Flatiron Institute, New York, New York 10010, USA
⁴Nano-Bio Spectroscopy Group, Universidad del País Vasco UPV/EHU, 20018 San Sebastián, Spain

^*Corresponding author. ofer.neufeld@gmail.com
^†Corresponding author. angel.rubio@mpsd.mpg.de

Article Text

Click to Expand

Supplemental Material

Click to Expand

References

Click to Expand

Issue

Vol. 127, Iss. 12 — 17 September 2021

Reuse & Permissions

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
Bulk photocurrent generation in diamond by THz cocircular $ω - 2 ω$ fields. (a) Schematic Lissajous curve for the time-dependent polarization of the field in Eq. (1) (for $ϕ = 0$ , $Δ = \sqrt{2}$ ). Small arrows indicate the direction of time, and the red arrow indicates the direction of the photocurrent ( $I$ ). Different instances in time are highlighted to emphasize the mirror symmetry of the Lissajous about its $x$ axis, but not the $y$ axis. (b) Calculated current expectation value (see Supplemental Material [37] for details) for laser field polarized in the (111) planes (with $λ = 2500 nm$ , $ϕ = 0$ , $Δ = \sqrt{2}, I_{0} = 7.5 \times 10^{12} W / {cm}^{2}$ ). The current is given in $10^{- 3}$ atomic units.
Reuse & Permissions
Figure 2
Numerical investigation of nonlinear photocurrents in diamond. (a) Photocurrent amplitude vs the field power (for $λ = 1200 nm$ , $ϕ = 0$ , $Δ = \sqrt{2}$ ). The plot is partitioned to different regimes as indicated by dashed lines. $I_{0}$ is given in logarithmic scale. (b) Photocurrent direction in the (111) planes with respect to the field’s $x$ axis (blue) and photocurrent amplitude (red) vs the field’s orientation with respect to the lattice (for $λ = 1200 nm$ , $Δ = 1$ , $I_{0} = 7.5 \times 10^{12} W / {cm}^{2}$ ). The current is given in $10^{- 3}$ atomic units.
Reuse & Permissions
Figure 3
Conduction band occupations in diamond after interaction with $ω - 2 ω$ cocircular laser, and photocurrent proportionality to the pulse duration. (a),(b) CB occupations (denoted by $ρ$ ) along $k_{x}^{'}$ and $k_{z}^{'}$ axes, respectively, integrated over the other two axes, presented in the coordinate system of the lattice ( $k_{y}^{’}$ is not shown due to similarity to $k_{x}^{'}$ ). $ρ$ is normalized to the density of states, $g (k^{'})$ . Purple curves show the CB occupation, while blue curves show the deviation from inversion symmetry (i.e., the occupations subtracted from their inverted image), indicating which states contribute to the photocurrent. Calculated for $λ = 1200 nm$ , $ϕ = 0$ , $Δ = \sqrt{3}$ , $I_{0} = 7.5 \times 10^{12} W / {cm}^{2}$ . (c) Photocurrent amplitude vs pulse duration. Inset shows calculation for a 25-cycle pulse showing the build-up of photocurrent from cycle to cycle. Calculated for the same parameters as (a) except $Δ = \sqrt{2}$ . The current is given in $10^{- 3}$ atomic units.
Reuse & Permissions
Figure 4
Spontaneous symmetry breaking in extremely nonlinear photocurrents in diamond. (a) Total excitation of electrons to the CB per primitive cell vs $I_{0}$ . Inset shows the electron occupation on the VBs during interaction with the laser pulse for the exemplary case of $I_{0} = 5 \times 10^{13} W / {cm}^{2}$ , showing that the VB is quickly depopulated even during the turn-on of the laser pulse. (b) Deviation in photocurrent amplitudes between the IPA and the TDDFT calculation vs field power (for $λ = 1200 nm$ , $ϕ = 0$ , $Δ = \sqrt{3}$ , $I_{0} = 5 \times 10^{13} W / {cm}^{2}$ ). (c) Calculated photocurrent amplitudes vs CEP, showing that CEP sensitivity arises in the extremely strong-field regime. Calculated for the same parameters as (a), except with $Δ = \sqrt{2}$ . The current is given in $10^{- 3}$ atomic units.
Reuse & Permissions

Physical Review Letters