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...
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2025-04-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-025-96448-y |
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| author | G. Coslovich R. P. Smith S.-F. Shi J. H. Buss J. T. Robinson F. Wang R. A. Kaindl |
| author_facet | G. Coslovich R. P. Smith S.-F. Shi J. H. Buss J. T. Robinson F. Wang R. A. Kaindl |
| author_sort | G. Coslovich |
| collection | DOAJ |
| description | 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. |
| format | Article |
| id | doaj-art-3fdfca3bb3ff442cbe467bec76334672 |
| institution | DOAJ |
| issn | 2045-2322 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj-art-3fdfca3bb3ff442cbe467bec763346722025-08-20T03:13:55ZengNature PortfolioScientific Reports2045-23222025-04-0115111010.1038/s41598-025-96448-yUltrabroadband THz conductivity of gated graphene in- and out-of-equilibriumG. Coslovich0R. P. Smith1S.-F. Shi2J. H. Buss3J. T. Robinson4F. Wang5R. A. Kaindl6Materials Sciences Division, Lawrence Berkeley National LaboratoryMaterials Sciences Division, Lawrence Berkeley National LaboratoryMaterials Sciences Division, Lawrence Berkeley National LaboratoryMaterials Sciences Division, Lawrence Berkeley National LaboratoryU.S. Naval Research LaboratoryMaterials Sciences Division, Lawrence Berkeley National LaboratoryMaterials Sciences Division, Lawrence Berkeley National LaboratoryAbstract 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.https://doi.org/10.1038/s41598-025-96448-y |
| spellingShingle | G. Coslovich R. P. Smith S.-F. Shi J. H. Buss J. T. Robinson F. Wang R. A. Kaindl Ultrabroadband THz conductivity of gated graphene in- and out-of-equilibrium Scientific Reports |
| title | Ultrabroadband THz conductivity of gated graphene in- and out-of-equilibrium |
| title_full | Ultrabroadband THz conductivity of gated graphene in- and out-of-equilibrium |
| title_fullStr | Ultrabroadband THz conductivity of gated graphene in- and out-of-equilibrium |
| title_full_unstemmed | Ultrabroadband THz conductivity of gated graphene in- and out-of-equilibrium |
| title_short | Ultrabroadband THz conductivity of gated graphene in- and out-of-equilibrium |
| title_sort | ultrabroadband thz conductivity of gated graphene in and out of equilibrium |
| url | https://doi.org/10.1038/s41598-025-96448-y |
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