Cooper-pair formation by anharmonic rattling modes in the β-pyrochlore superconductor KOs2O6

Novel vortex distribution in the β-pyrochlore superconductor KOs2O6

By utilizing the micro-Hall probe array, we study the superconducting and the vortex states in a single crystal of KOs2O6 near the first-order transition at Tp ∼ 8 K, which is associated with a change in the rattling motion of K ions. We show that below the first-order transition, the lower critical field exhibits a distinct decrease, suggesting that the electron-phonon coupling is weakened bel...

Effects of Rattling Phonons on the Dynamics of Quasiparticle Excitation in the -Pyrochlore KOs2O6 Superconductor

Correlation effects and structural dynamics in the b-pyrochlore superconductor KOs2O6

Electronic, magnetic, and dynamical properties of superconducting b-pyrochlore KOs2O6 and related RbOs2O6 and CsOs2O6 compounds are calculated and compared with experiment and contrasted with structurally related spinel pyrochlores. The calculated susceptibility Stoner enhancement (110%) and thermal mass enhancement l=2.5–3 reflect moderate but perhaps important Coulomb correlations. The K+ ion...

Frustration in the coupled rattler system KOs2O6

Starting from ab initio electronic structure results we study dynamics of potassium ions in the pyrochlore superconductor KOs2O6. An effective ionic Hamiltonian characterized by an on-site instability rattler and frustrated nearest-neighbor interaction is derived and various approximations are investigated. We show that qualitative differences in the properties of KOs2O6 and its analogs RbOs2O6...

Visualizing Cooper Pair Formation on the Atomic Scale in High Temperature Superconductors By

In the quest for a microscopic theory for the superconductivity in cuprates, one hotly debated issue is the temperature at which Cooper pairs first form. Do pairs form at the critical temperature Tc or do they form at higher temperatures lacking phase rigidity? To answer the question, we have developed new techniques, based on scanning tunneling microscopy, to visualize the process of the pair ...