Electronic and magnetic properties of armchair MoS2 nanoribbons under both external strain and electric field, studied by first principles calculations

Abstract

The electronic and magnetic properties of armchair edge MoS2 nanoribbons (MoS2-ANRs) underboth the external strain and transverse electric field (Et) have been systematically investigated by using the first-principles calculations. It is found that: (1) If no electric field is applied, an interesting structural phase transition would appear under a large tensile strain, leading to a new phase MoS2-A'NR, and inducing a big jump peak of the band gap in the transition region. But, the band gap response to compressive strains is much different from that to tensile strain, showing no the structural phase transition. (2) Under the small tensile strains (<10%), the combined Et and tensile strain give rise to a positive superposition (resonant) effect on the band gap reduction at low Et (<3 V/nm), and oppositely a negative superposition (antiresonant) one at high Et (>4 V/nm). On the other hand, the external compressive strains have always presented the resonant effect on the band gap reduction, induced by the electric field. (3) After the structural phase transition, an external large tensile strain could greatly reduce the critical field Etc causing the band gap closure, and make the system become a ferromagnetic (FM) metal at a relative low Et (e.g., <4 V/nm), which is very helpful for its promising applications in nano-mechanical spintronics devices. (4) At high Et (>10 V/nm), the magnetic moments of both the MoS2-ANR and MoS2-A'NR in their FM states could be enhanced greatly by a tensile strain. Our numerical results of effectively tuning physical properties of MoS2-ANRs by combined external strain and electric field may open their new potential applications in nanoelectronics and spintronics.