One of the central features of the now half-century old theory of the microscopic origins of superconductivity in elemental materials is the correlations between pairs of electrons with opposite spin and momentum. The constituent electrons of these Cooper pairs have the unusual property that their mean spatial separation is much larger than atomic length scales, extending hundreds of nanometers in some materials. The central question motivating this thesis is whether one can see effects of these electronic correlations by placing normal metal probes on a superconductor within this length scale of each other. In particular we search for empirical evidence of two predicted processes, crossed Andreev reflection and elastic cotunneling, in which the Cooper pairs in a superconductor coherently couple electrons in two normal metal probes. We present results showing that such coupling does indeed occur and its observed behavior is consistent with the predicted processes. Specifically, we show that signals can be sent between normal metal probes which are nonlocal, phase coherent, and decay on the order of the Cooper pair correlation length. In addition, our data give new insights into the interaction between normal electrons and Cooper pairs when they coexist in a normal metal.

Last modified

• 09/13/2018

Creator

• Paul Cadden-Zimansky

DOI

• https://doi.org/10.21985/N25159

Subject

• Physics and Astronomy

Keyword

• Astronomy
• Physics

Date created

• 2008-09-19

Resource type

• Dissertation

Rights statement

• In Copyright