2020, Direct Observation of Linear Dichroism Transition in Two-dimensional Palladium Diselenide. Nano Letters.
Direct Observation of Linear Dichroism Transition in Two-dimensional Palladium Diselenide, Nano Letters.
ABSTRACT:
Linear dichroism (LD) transition within anisotropic photonic materials display promising prospects for applications in polarization-wavelength selective detectors, optical switching, and optical communication. In conventional two-dimensional (2D) anisotropic materials, the LD is predominantly uniaxial over a broad spectrum of wavelengths and arises principally due to the reduced symmetry of the materials. However, the LD transition behavior in crystalline 2D materials remains elusive. Here, we demonstrate the observation of a unique LD conversion phenomenon at a wavelength of 472 nm in Palladium diselenide (PdSe2) using polarization-resolved absorption spectroscopy. This material exhibits prominent anisotropic responses and high absorption ratios of αy/αx1.11 at 364 nm, 1.15 at 532 nm, and 0.84 at 633 nm. We propose that this abnormal LD conversion behavior originates from the forceful localization rules at different parallel energy bands that exist within this material. Furthermore, the robust periodicity of Ag and B1g modes in polarization-resolved Raman spectroscopy is in a good agreement with the theoretical structure symmetry analysis. This indicates the strong intrinsic LD effect in the anisotropic nature of PdSe2, which offers a macro-level determination of crystal orientations. Such unique LD conversion features, in combination with strong LD effects, enable the air-stable PdSe2 a potential candidate for technological innovations in multispectral imaging, sensing, polarization-sensitive, and wavelength-controllable photoelectronic applications.
KEYWORDS: 2D material, Palladium diselenide, Linear dichroism transition, Anisotropy
Link: https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.9b04598