Electronic phase transition, vibrational properties and structural stability of single and two polyyne chains under external electric field

Search for one dimensional (1D) van der Waals materials has become an urgent need to meet the demand as building blocks for high performance, miniaturized, lightweight device applications. Polyyne, a 1D atomic chain of carbon is the thinnest and strongest allotrope of carbon, showing promising applications in new generation low dimensional devices due to the presence of a band gap. A system of two carbon chains held together by van der Waals interaction has been theoretically postulated and shows band gap tunability under structural changes which finds applications in the realms of resistive switching and spintronics. In this study, we use first principles Density Functional Theory (DFT) to show a sharp semiconductor to metal transition along with the emergence of an asymmetry in the spin polarized density of states for single and two polyyne chains under a transverse electric field. The thermodynamic stability of the system has been substantiated through the utilization of Ab Initio Molecular Dynamics (AIMD) simulations, phonon dispersion curve analyses, and formation energy calculations. Furthermore, in addition to its dynamic stability assessment, phonon calculations have served to identify Raman-active vibrational modes which offers an invaluable non-destructive experimental avenue for discerning electronic phase transitions in response to an applied electric field. Our study presents a predictive framework for the prospective utilization of one and two polyyne chains in forthcoming flexible nano-electronic and spintronic devices. The future prospects of the system are contingent upon advancements in nano-electronics fabrication techniques and the precise construction of circuitry for harnessing spin-related applications.