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Description
Symmetry breaking underpins a wide range of nonlinear physical phenomena [1–4]. Specifically, tailored light–matter interactions with graphene, a highly symmetric two dimensional material, provide a powerful platform for probing such symmetry breaking through photocurrent spectroscopy. Using two linearly polarized harmonic fields with independent control over relative polarization angle and temporal delay, we systematically map photocurrent selection rules arising from the interplay of the driving field and the material symmetries [2,5,6]. In inversion-symmetric graphene, two-color photocurrents predominantly originate from injection currents associated with asymmetric carrier populations in the conduction bands. Time-reversal symmetry (TRS) enforces equal excitation probabilities at conjugate momenta, resulting in symmetry-protected suppression of injection currents when TRS is preserved. Using biharmonic field synthesis, we selectively break or maintain TRS and mirror symmetry, enabling direct identification of symmetry-dependent current suppression and phase-dependent photocurrent generation. Our experimental results are quantitatively benchmarked against state-of-the-art time-dependent density functional theory (TDDFT) simulations. We further extend this approach to systems with intrinsically broken TRS, including the magnetic van der Waals material CrI$_3$ and an inversion-symmetric Floquet topological insulator. Simulated two-color photocurrent responses in these systems exhibit qualitatively distinct phase dependencies, highlighting the sensitivity of this method to underlying symmetry properties. Overall, our work establishes photocurrent suppression of ultrafast, linearly polarized two-color fields as a direct, versatile and noninvasive probe of symmetry-broken phases of matter, without the need for magnetic fields or circularly polarized light [7].
[1] D. Ayuso et al., Nat. Photonics 13, 866-871 (2019).
[2] O. Neufeld et al., Phys. Rev. Lett. 127, 126601 (2021).
[3] D. Habibović et al., Nat. Rev. Phys. 6, 663-675 (2024).
[4] O. Neufeld, ACS Photonics (2025).
[5] I. Franco and P. Brumer, J. Phys. B: At. Mol. Opt. Phys. 41, 074003 (2008).
[6] M. Shapiro and P. Brumer, ISBN 9783527409044 (2011).
[7] D. M. B. Lesko et al., ACS Nano (2026)