Department of Mechanical Engineering
Kenneth E. Goodson
Flik, M.I., Zhang, Z.M., Goodson, K.E., Siegal, M.P., and Phillips, J.M., 1992, "The Electron Scattering Rate in Epitaxial YBa2Cu3O7 Superconducting Films," Physical Review B, Vol. 46, pp. 5606-5614.
This work determines the electron scattering rate in the a-b plane of epitaxial YBa2Cu3O7 films using two techniques. Infrared spectroscopy yields the scattering rate at temperatures of 10, 78, and 300K by fitting reflectance data using thin-film optics and a model for the free-carrier conductivity. The scattering rate is also obtained using kinetic theory and an extrapolation of normal-state electrical resistvity data to superconducting temperatures based on the Bloch theory for the phonon-limited electrical resistivity of metals. The scattering rates determined using both techniques are in agreement and show that the electron mean free path in the a-b plane of YBa2Cu3O7 superconducting films is three to four times the coherence length. Hence YBa2Cu3O7 is pure but not in the extreme pure limit. An average defect interaction range of 4 nm is obtained using the defect density resulting from flux-pinning considerations.