E. Bielejec et al., Anisotropic magnetoconductance in quench-condensed ultrathin beryllium films - art. no. 100502, PHYS REV B, 6310(10), 2001, pp. 0502
Near the superconductor-insulator (S-I) transition, quench-condensed ultrat
hin Be films show a large magnetoconductance which is highly anisotropic in
the direction of the applied field. Film conductance can drop as much as s
even orders of magnitude in a weak perpendicular field (less than or equal
to1 T), but is insensitive to a parallel field in the same field range. We
believe that this negative magnetoconductance is due to the field dephasing
of the superconducting pair wave function. This idea enables us to extract
the finite superconducting phase coherence length, L-phi, in nearly superc
onducting films. Our data indicates that this phase coherence persists even
in highly insulating films in the vicinity of the S-I transition. In nearl
y insulating films, we observe that at low temperatures L-phi decreases wit
h decreasing temperature. This is rather counterintuitive since L-phi is ex
pected to increase with decreasing temperature as inelastic phonon scatteri
ng is suppressed.