Ultrabroadband THz conductivity of gated graphene in- and out-of-equilibrium
Abstract We employ ultrabroadband terahertz (THz) spectroscopy to expose the high-frequency transport properties of Dirac fermions in monolayer graphene. By controlling the carrier concentration via tunable electrical gating, both equilibrium and transient optical conductivities are obtained for a r...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-04-01
|
| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-025-96448-y |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Abstract We employ ultrabroadband terahertz (THz) spectroscopy to expose the high-frequency transport properties of Dirac fermions in monolayer graphene. By controlling the carrier concentration via tunable electrical gating, both equilibrium and transient optical conductivities are obtained for a range of Fermi levels. The frequency-dependent equilibrium response is determined through a combination of time-domain THz and Fourier-transform infrared spectroscopy for energies up to the near-infrared, which also provides a measure of the gate-voltage dependent Fermi level. Transient changes in the real and imaginary parts of the graphene conductivity are electro-optically resolved for frequencies up to 15 THz after near-infrared femtosecond excitation, both at the charge-neutral point and for higher electrostatic-doping levels. Modeling of the THz response provides insight into changes of the carrier spectral weights and scattering rates, and reveals an additional broad-frequency ( $$\approx$$ 8 THz) component to the photo-induced response, which we attribute to the zero-momentum mode of quantum-critical transport observed here in large-area CVD graphene. |
|---|---|
| ISSN: | 2045-2322 |