Nonlinear elastic and electronic properties of Mo_6S_3I_6 nanowires

TL;DR

This study uses ab initio calculations to explore the nonlinear elastic and electronic properties of Mo_6S_3I_6 nanowires, revealing their potential for strain sensing and quantum physics investigations due to their strong anisotropy and 1D behavior.

Contribution

First detailed ab initio analysis of Mo_6S_3I_6 nanowires' elastic and electronic properties highlighting their unique 1D characteristics and potential applications.

Findings

Young's modulus varies between 82 GPa and 94 GPa under strain.

Chains break at Mo-Mo bonds within octahedra, not in S bridges.

Conductivity is highly strain-sensitive and anisotropic.

Abstract

The properties of Mo_6S_3I_6 nanowires were investigated with ab initio calculations based on the density-functional theory. The molecules build weakly coupled one-dimensional chains with three sulfur atoms in the bridging planes between the Mo octahedra, each dressed with six iodines. Upon uniaxial strain along the wires, each bridging plane shows two energy minima, one in the ground state with the calculated Young modulus Y=82 GPa, and one in the stretched state with Y=94 GPa. Both values are at least four times smaller than the experimental values and the origin of the discrepancy remains a puzzle. The ideal tensile strength is about 8.4 GPa, the chains break in the Mo-Mo bonds within the octahedra and not in the S bridges. The charge-carrier conductivity is strongly anisotropic and the Mo_6S_3I_6 nanowires behave as quasi-one-dimensional conductors in the whole range of investigated strains. The conductivity is extremely sensitive to strain, making this material very suitable for stain gauges. Very clean nanowires with good contacts may be expected to behave as ballistic quantum wires over lengths of several $\mu $m. On the other hand, with high-impedance contacts they are good candidates for the observation of Luttinger liquid behaviour. The pronounced 1D nature of the Mo_6S_3I_6 nanowires makes them a uniquely versatile and user-friendly system for the investigation of 1D physics.