Hyunjeong Kim Thesis Defense 12/8/11

Thesis Defense

Hyunjeong Kim

Thursday, December 8, 2011
1:00pm (334 JFB)

Title: TBD

Abstract:

In the field of one-dimensional superconductor an open question exists as whether the state of a superconducting wire is determined by local physics or some global (or external) parameters such as normal state resistance, shunt resistor, wire length, dissipative coupling, quantum state or impedance of connected electrodes. To address the question we have studied transport properties of very narrow (9-20nm) homogenous amorphous MoGe wires fabricated by advanced electron-beam lithography in wide range of length 1-25mm. We observed that the wires undergo a superconductor-insulator transition that is controlled by cross sectional area of a wire, i.e. local physics. Mean-field critical temperature decreases exponentially with a wire cross section: the reduction is likely fermionic, due to enhancement of Coulomb repulsion. After losing superconductivity, the resistance of the wires increases monotonically with decreasing temperature and show a conductance dip at zero bias voltage. This zero bias anomaly in insulating wires has signature of both Coulomb blockade and perturbative electron-electron interaction in1D..

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