The superconductor to insulator transition
Most people are familiar with the onset of superconductivity from a metallic phase or with the well known metal-insulator transition. Recently it has been proposed that at zero temperature in disordered two-dimensional films it should be possible to study a direct superconductor-insulator transition. Experimentally such a transition can be tuned through by varying the thickness and thereby the disorder in for example Bi films. The transition is in this case between a novel insulating Bose glass' phase and a superconducting state. Surprisingly, no metallic phase is believed to exist in two dimensions at zero temperature but a superconducting phase is allowed. However, right at the critical point, between the insulating and superconducting phase, these amorphous films should behave as metals and have a finite universal conductivity [sigma][sup *]. Experiments indicate that this universal conductivity should be approximately 1/(6.45 k[Omega]). In this thesis the 2-D zero-temperature superconductor-insulator transition is studied by Monte Carlo simulations of interacting bosons (Cooper pairs) moving in a quenched random potential. The authors calculate the universal conductivity [sigma][sup *] and the critical exponents and the superconductor-insulator transition. For short-range repulsive interactions they find [sigma][sup +] = (0.14 [+-] 0.03)[sigma][sub Q][sup [minus]1] [triple bond] R[sub Q] [triple bond] h/(2e)[sup 2] [approx equal] 6.45 k[Omega], and for long-range Coulomb interactions they find [sigma][sup +] = (0.55 [+-])[sigma][sub Q].
- Research Organization:
- California Univ., Santa Cruz, CA (United States)
- OSTI ID:
- 6982330
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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