Stable anisotropic single-layer of ReTe$_2$: a first principles prediction


Abstract: In order to investigate the structural, vibrational, electronic, and mechanical features of single-layer ReTe$_2$ first-principles calculations are performed. Dynamical stability analyses reveal that single-layer ReTe$_2$ crystallize in a distorted phase while its 1H and 1T phases are dynamically unstable. Raman spectrum calculations show that single-layer distorted phase of ReTe$_2$ exhibits 18 Raman peaks similar to those of ReS$_2$ and ReSe$_2$. Electronically, single-layer ReTe$_2$ is shown to be an indirect gap semiconductor with a suitable band gap for optoelectronic applications. In addition, it is found that the formation of Re-units in the crystal induces anisotropic mechanical parameters. The in-plane stiffness and Poisson ratio are shown to be significantly dependent on the lattice orientation. Our findings indicate that single-layer form of ReTe$_2$ can only crystallize in a dynamically stable distorted phase formed by the Re-units. Single-layer of distorted ReTe$_2$ can be a potential in-plane anisotropic material for various nanotechnology applications.

Keywords: Density functional theory, in-plane anisotropic 2D materials, phonons and vibrational spectrum

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