Hydrogen doping induced px±ipy triplet superconductivity in quasi-one-dimensional K2Cr3As3

Abstract

Quasi-one-dimensional Cr-based superconductor K2Cr3As3 has aroused great research interest due to its possible triplet pairing symmetry. Recent experiments have shown that incorporating hydrogen into K2Cr3As3 would significantly change its electronic and magnetic properties. Hence, it is necessary to investigate the impact of hydrogen doping in the pairing symmetry of this material. Employing the hydrogen as a nontrivial electron doping, our calculations show that the system exhibits px±ipy-wave pairing symmetry under specific hydrogen doping, in contrast with the pz-wave one obtained without hydrogen. Specifically, we adopt the random-phase-approximation approach based on a six-band tight-binding model equipped with multiorbital Hubbard interactions to study the hydrogen doping dependence of the pairing symmetry and superconducting Tc. Under the rigid-band approximation, our pairing phase diagram shows that the spin-triplet pairing covers the hydrogen doping regime x∈(0,0.7). In particular, the Tc∼x curve shows a peak at the 3D-quasi-1D Lifshitz transition point, and the pairing symmetry near this doping level is px±ipy. The physical origin of this pairing symmetry is that the density of states is mainly contributed from momenta with large kx(ky) components on the Fermi surface. Due to the three-dimensional characteristic of the real material, this px±ipy-wave pairing possesses a point-node gap. We further provide experiment predictions to identify this triplet px±ipy-wave superconductivity.

Source-reported materials — not catalogue approval

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