Heat Capacity of Superconducting Nanowires
Open Access
- Author:
- Kurtz, James Sampson
- Graduate Program:
- Physics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- August 22, 2005
- Committee Members:
- Moses Hung Wai Chan, Committee Chair/Co-Chair
- Keywords:
- superconductivity
specific heat
heat capacity
nanowires - Abstract:
- The Mermin-Wagner Theorem of critical phenomena states that systems with order parameters of continuous symmetry, like the superconducting state, exhibit no long-range order for spatial dimensions less than or equal to two. The study of superconductors in highly confined geometries that approach this limit has been an active area of research for some decades, as the details have been explored of how this robust phase in three-dimensions is destroyed by thermal fluctuations for progressively more severe confinement. Interesting results have been reported in particular for electrical transport in thin wires, though there has been controversy over the role of the material’s morphology in the observed weakening of the superconducting state. With this in mind, we sought to contribute a new perspective on this system by performing the first heat capacity measurements of one-dimensional superconductors. We have utilized new techniques for producing thin, high quality nanowires of various metals with high crystallinity, diameters well below the superconducting coherence length, and in quantities massive enough to be used for thermodynamic studies. The heat capacity measurements on arrays of these nanowires indicate that despite the one-dimensional transport effects observable at these diameters, the thermodynamic signature of superconducting order is surprisingly bulk-like. These results demonstrate, then, that the crossover regime from three-dimensional behavior to one-dimensional behavior in these superconducting nanowires is quite dependent upon the measurement in question. In the case of these nanowires, whose diameters are several times smaller than the coherence length, superconducting order is quite robust locally even as it succumbs to thermal fluctuations on longer length scales.