Electronic and magnetic properties of the two-dimensional C4H-type polymer with strain effects, intrinsic defects and foreign atom substitutions

Abstract

Following the two-dimensional periodic single-layer sheet successful synthesized experimentally very recently [Adv. Mater., 2011, 23, 4497], we present systematically the electronic and magnetic properties of this novel polymer (referred to as C₄H) without and with strain-modifying, vacancy-doping, and nonmetal element (B, N, and P) doping by means of first-principles calculations. It was found that: (a) the C₄H sheet is a nonmagnetic semiconductor with a wide indirect band gap. (b) The atomic structure, binding energies and electronic properties of the C₄H sheet could be significantly modified by applying strain. (c) Vacancy defects can lead to intrinsic magnetism in C₄H and, surprisingly, the induced spin polarization has large spatial extension; especially, room-temperature ferromagnetism in H vacancies-doped case is quite feasible. (d) Substitution of B, P and N at the unhydrogenated C site could form a local magnetic moment, whereas no spin-polarization could be induced for that with N at the hydrogenated C site. The present study provides theoretical insight leading to a better understanding of novel 2D structures, and further experimental studies are expected to confirm the attractive predictions.