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Anisotropic ultraviolet-plasmon dispersion in black phosphorus
Giuseppe Nicotra1, Edo van Veen, Ioannis Deretzis
1Istituto per la Microelettronica e Microsistemi (IMM-CNR), VIII Strada 5, I-95121 Catania, Italy. giuseppe.nicotra@imm.cnr.it.
Nanoscale
|November 21, 2018
Summary
We studied ultraviolet interband plasmons in black phosphorus using electron energy loss spectroscopy (EELS). The plasmon dispersion was found to be anisotropic, matching theoretical predictions and revealing new near-infrared excitations.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spectroscopy
Background:
- Black phosphorus exhibits unique electronic properties due to its anisotropic band structure.
- Understanding plasmonic modes is crucial for exploring light-matter interactions in low-dimensional materials.
Purpose of the Study:
- To investigate the dispersion relation of interband plasmonic modes in black phosphorus.
- To explore the anisotropy of these plasmonic excitations.
- To identify and characterize low-energy excitations in the near-infrared spectrum.
Main Methods:
- Momentum-resolved electron energy loss spectroscopy (EELS) combined with scanning transmission electron microscopy.
- Density functional theory (DFT) calculations.
- High-resolution EELS (HREELS) in reflection mode.
Main Results:
- Anisotropic dispersion relation observed for ultraviolet interband plasmons.
- Experimental findings are well-reproduced by DFT, considering band structure anisotropy and damping.
- Existence of low-energy, near-infrared excitations selectively active in the armchair direction confirmed.
Conclusions:
- The anisotropic band structure of black phosphorus dictates the anisotropic plasmon dispersion.
- DFT provides an accurate model for predicting plasmonic behavior in black phosphorus.
- Discovery of direction-selective near-infrared excitations opens new avenues for optoelectronic applications.
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