Symmetry-broken superconducting configurations from density functional theory for bcc and hcp metals and Nb3Sn

Abstract

We recently proposed a unified theoretical framework for superconductivity that broadens the applicability of Bardeen-Cooper-Schrieffer (BCS) theory to both conventional and unconventional superconductors. Within this framework, superconductivity arises from the formation of a symmetry-broken superconducting configuration (SCC) generated by atomic perturbations of the normal conducting configuration (NCC). The SCC emerges through electron-phonon interaction and gives rise to distinct straight one-dimensional tunnels (SODTs) in the charge density difference of electrons and/or holes. These SODTs originate from regular and systematic atomic displacements between the SCC and NCC, a phenomenon revealed by density functional theory (DFT) calculations. To further verify this framework, we performed DFT-based calculations for 12 hexagonal close-packed (hcp) elements (Be, Mg, Sc, Y, Ti, Zr, Hf, Tc, Re, Ru, Os, and Zn), 5 body-centered cubic (bcc) elements (V, Nb, Ta, Mo, and W), and the compound Nb3Sn. Our results indicate that all these materials exhibit superconductivity at 0 K and 0 GPa, as evidenced by the predicted SODTs. Notably, Mg, Sc, and Y are predicted to be superconducting under ambient pressure, a finding that awaits experimental confirmation.