Gapless superconductivity in bi₂sr₂c_acu₂o₈

Break-junction tunneling results are evaluated to obtain the excitation spectrum or density of states (DOS) in the superconducting state of Bi2Sr2CaCu208. At low temperatures the DOS follows N(E) - \E - Ef \ for energies close to the Fermi level and exhibits peaks separated by 2d = 72 meV. As the temperature is increased, the peak-to-peak distance decreases slightly and the states in between are rapidly filled up. There is also a temperature-independent feature in the DOS, with an energy scale 5 200 meV, most likely symmetric about EF.