Temperature Evolution of the Electronic States {\&} Multiple Gap Features in Bi$_{2}$Sr$_{2-y}$La$_{y}$CuO$_{6}$.

Like Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$, Bi$_{2}$Sr$_{2-y}$La$_{y}$CuO$_{6 }$samples show inhomogeneous gaps in the DOS at low temperature. We present atomic resolution STM spectroscopy measurements of the evolution of the DOS with temperature for optimal (y=0.4) and overdoped (y$<$0.4) samples and compare these measurements to Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$. In Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$, the low temperature (T$<$Tc) spectra of overdoped samples are all characterized by a single d-wave gap with sharp coherence peaks. In contrast, Bi$_{2}$Sr$_{2-y}$La$_{y}$CuO$_{6 }$shows a variety of spectra at low temperature ranging from those without gaps to ones with multiple gap features [1]. By measuring the temperature evolution of these gap features at given lattice sites for various doping levels, we estimate the local temperature at which pairing develops in these samples. [1] Boyer et al., Nat Phys 3, 802 (2007)