Pseudospin-selective Floquet band engineering in black phosphorus

Area of Science:

• Quantum Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Floquet engineering utilizes time-periodic light fields to control quantum states in various systems.
• Previous work has shown tailored material properties, but experimental evidence in semiconductors is lacking.
• Momentum-resolved Floquet band engineering is crucial for extending this technique to semiconductors.

Purpose of the Study:

• To provide the first experimental evidence of momentum-resolved Floquet band engineering in a semiconductor.
• To investigate light-induced modifications of electronic band structures in black phosphorus.
• To explore the role of lattice symmetry and polarization in Floquet band engineering.

Main Methods:

• Time and angle-resolved photoemission spectroscopy (TARPS) measurements.
• Near-resonance pumping of black phosphorus with a tunable light field (340–440 meV).
• Analysis of band renormalization, dynamical gap opening, and polarization-dependent effects.

Main Results:

• Observed strong band renormalization near the band edges of black phosphorus.
• Resolved light-induced dynamical gap opening at resonance points, coinciding with Floquet sidebands.
• Demonstrated pseudospin selectivity in band renormalization, favoring armchair polarization due to lattice symmetry.

Conclusions:

• Successfully demonstrated pseudospin-selective Floquet band engineering in the semiconductor black phosphorus.
• The findings provide crucial experimental validation and guiding principles for future Floquet engineering of semiconductors.
• This work opens new avenues for controlling electronic and optical properties of semiconductor materials using light.