FIGURE 2. Data obtained at high spatial resolution, showing the typical spatial interrelationship of and G() for underdoped Bi-2212.

These data were generated from a single 128 128 pixel spectral survey which was taken on the 147 Å 147 Å region inside the white box in Fig. 1a. This spectral survey was taken several weeks after the survey used to calculate Fig. 1a, during which the sample was kept continuously at 4.2 K. a, High-resolution gap map revealing approximately 12 -domains embedded in the percolative -like background. b, Map of G() at the same location as a. Here, to reveal the spatial correlations between and G(), we use the same colour bar as in a but here the scale is inverted and represents G(). Note that G() is defined as the gap-edge peak at negative bias throughout this Letter. In c we show the spatial evolution of and in d of G() along the trajectory of the white line seen in a and b. Figures 2 and 3 together illustrate the properties of the two distinct types of regions. In terms of , the -domains are defined by a distinct value of which is 50 meV and which is constant to 5% within a 13-Å radius of the centre of each domain, while the -regions are defined by 35 meV. There exists an overlap range of (35 meV 50 meV) in which categorization must rely on parameters in addition to . The tick mark on the colour scale is at 42 meV at the centre of this overlap range. In terms of G(), the -domains are defined by G() at the centre of the domain being 66% ( = 23%) above the average -region G(), which itself has = 15%. Similar conclusions are derived from all equivalent maps from other underdoped spectral surveys. The spectral survey was acquired with constant current normalization at 4.2 K with tunnel junction resistance of 1 G set at V = -200 mV.