Scattering Interference Signature of Hidden Orbital Orderin Superconducting CeCoIn₅

Visualizing orbital degrees of freedom and orders is a new challenge in scanned microscopy. Some types of orbital order(OO) are virtually imperceptible because they do not reduce the overall crystal symmetry. Recently, however, direct visualization of quasiparticle scattering interference(QPI) has become a powerful technique for detecting OO states[1,2]. Hence, we model the QPI of (π,π) OO in both normal and superconductive phases and find distinct, sublattice-specific scattering interference patterns generated by OO,  which we predict to be strongly enhanced in the latter phase. Sublattice-resolved QPI visualization in superconducting CeCoIn₅ then reveals two orthogonal QPI signatures at impurity atoms, with each QPI pattern specific to one sublattice. This discovery implies that QPI is a powerful technique to detect the hidden global symmetry-preserving orbital order in superconductors.