We a describe a measurement of the spin Knight shift (Ks) around the middle point between two vortices as a function of magnetic field (H) up to 28 T in a high-Tc superconductor TlSr2CaCu 2O6.8. At low temperatures, Ks increases substantially with increasing field, which indicates that the quasiparticle states with an ungapped spectrum are extended outside the vortex cores in a d-wave superconductor. The density of such states is found to be ∼0.7N 0√H/Hc2, with No being the normal-state density of states and Hc2 being the upper critical field.
- D-wave superconductor
- Quasiparticle state
ASJC Scopus subject areas
- Statistical and Nonlinear Physics
- Condensed Matter Physics