Interplay of Hidden Orbital Order and Superconductivity in CeCoIn5

TL;DR

This paper proposes a novel quasiparticle scattering interference (QPI) method to visualize hidden orbital order in superconducting CeCoIn5, revealing sublattice-specific signatures that intertwine with d-wave superconductivity.

Contribution

It introduces a sublattice-resolved QPI technique to detect elusive orbital order in superconductors, demonstrating its effectiveness in CeCoIn5.

Findings

Sublattice-specific QPI signatures emerge strongly in the superconducting phase.

Orthogonal QPI patterns are observed at impurity sites.

QPI intensity peaks near the Fermi level, indicating intertwined orbital order and superconductivity.

Abstract

Visualizing atomic-orbital degrees of freedom is a frontier challenge in scanned microscopy. Some types of orbital order are virtually imperceptible to normal scattering techniques because they do not reduce the overall crystal lattice symmetry. A good example is dxz/dyz ({\pi},{\pi}) orbital order in tetragonal lattices. For enhanced detectability, here we consider the quasiparticle scattering interference (QPI) signature of such ({\pi},{\pi}) orbital order in both normal and superconducting phases. The theory reveals that sublattice-specific QPI signatures generated by the orbital order should emerge strongly in the superconducting phase. Sublattice-resolved QPI visualization in superconducting CeCoIn5 then reveals two orthogonal QPI patterns at lattice-substitutional impurity atoms. We analyze the energy dependence of these two orthogonal QPI patterns and find the intensity peaked near E=0, as predicted when such ({\pi}) orbital order is inte,{\pi}rtwined with d-wave superconductivity. Sublattice-resolved superconductive QPI techniques thus represent a new approach for study of hidden orbital order.