Controlling quantum materials with time-periodic drive*

Time-periodic light-field can dress the electronic states of quantum materials, providing a fascinating controlling knob for transient modifications of the electronic structure with light-induced emergent phenomena [1]. In this talk, I will present our recent experimental progress on the Floquet engineering of two-dimensional materials using time- and angle-resolved photoemission spectroscopy (TrARPES). Using black phosphorus as an example, I will present the light-induced manipulation of the transient electronic structure in two different pumping regimes: near-resonance pumping and far below-gap pumping. A modification of the valence band from parabolic to a Mexican-hat like dispersion is observed upon near-resonance pumping with the band gap, and intriguing light polarization dependence is observed, reflecting the intriguing pseudospin selectivity in the Floquet engineering [2]. By further pushing the pump beam to even lower photon energy [3], we found that transient manipulation of the electronic structure can also be achieved by far below-gap pumping, yet with distinctive behavior near the top of the valence band. Based on what we have learned from these works, insights for extending Floquet engineering to more materials will also be discussed.

 

[1] Changhua Bao et al., “Light-induced emergent phenomena in two-dimensional materials and topological materials”, Nat. Rev. Phys. 4, 33 (2022)

[2] Shaohua Zhou⁺, Changhua Bao⁺ et al., “Pseudospin-selective Floquet band engineering in black phosphorus”, Nature 614, 75 (2023)

[3] Shaohua Zhou⁺, Changhua Bao⁺, et al., “Floquet engineering of black phosphorus by below-gap pumping”, Phys. Rev. Lett. 131, 116401 (2023)