We find a lattice instability in the superconductor KCr3As3, corresponding to a distortion of the Cr metallic wires in the crystal structure. This distortion couples strongly to both the electronic and magnetic properties, in particular by making the electronic structure much more nearly onedimensional, and by shifting the compound away from magnetism. We discuss the implications of these results in the context of the possibly unconventional superconductivity of this phase.
superconductors exhibit a variety of fascinating phenomena such as the Kosterlitz−Thouless−Berezinskii transition, electron quantum confinement effect, charge density wave, and topologically non-trivial band. Until now, the superconductivity of a classical elemental 2D system of tin has not yet been confirmed. Herein, using the microscopic theory of Bardeen, Cooper, and Schrieffer (BCS) and density functional theory calculations, we meticulously study the electron−phonon coupling, electronic structures, and phase transition of low-buckled (LB) stanene and high-buckled (HB) 2D tin. We demonstrate that the HB 2D tin exhibits remarkable multi-gap electron−phonon coupling superconductivity with critical temperatures approximating those of the conventional bulk tin and few-layer LB stanene. Our results clearly show the strain-induced transitions of the orbital occupation, band structure, and superconductivity from LB to HB structures. Our discovery of HB 2D tin as an excellent 2D superconductor should stimulate the experimental synthesis and characterization of its superconducting properties.
2D materials with Dirac cones, which show a linear band character near the Fermi level, exhibit many novel properties. Herein, based on first‐principles calculations, the 2D phosphorus carbide (
PC
5
) monolayer is studied systematically. The stability is examined by calculating the formation energy, phonon dispersion, and elastic constants as well as by performing ab initio molecular dynamics (AIMD) simulations. Due to the similarity of its structure to that of graphene, one Dirac cone is exactly located at the Fermi level, which is very robust against external biaxial and uniaxial strains. Treating the
PC
5
monolayer as graphene with doped P atoms along the armchair direction, a
3
N
rule is found similar to that of graphene nanoribbons with armchair edges. These physical properties make the
PC
5
monolayer a promising 2D material for emerging electronics applications.
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