Atomic-scale spatial modulation in the overdoped Bi-2212 density of states in register with the crystalline supermodulation

YANINA FASANO; G. LEVY; M. KUGLER; A. A. MANUEL; Ø. FISCHER; P.PEDRAZZINI; G. NIEVA

Les Diablerets, Switzerland

Workshop; 2005 Swiss Workshop on Materials with Novel Electronic Properties-Basic Research and Applications; 2005

  By means of low temperature scanning tunnelling microscopy in overdoped Bi-2212 (Tc = 78K) we reveal an atomic-scale density-of-states modulation in the oxygen-rich region of the superconducting phase diagram. We find a spatial variation of the tunnel conductance that has the same wavelength and is coupled with the underlying crystalline supermodulation. Even though our measurements are achieved with atomic resolution, we do not detect any interference pattern on the density of states, as reported in samples with doping levels of the order of, or smaller than, the optimal [1]. Our results in the overdoped region contrast with previous studies in underdoped and as-grown samples [1], indicating that the reported superconducting quasi-particle interference is ubiquitous. They also suggest that this phenomenon strongly depends on the local distribution of oxygen inhomogeneities, since it is not detected in the overdoped samples we studied.