Paramagnetic reentrant effect in high purity mesoscopic AgNb proximity structures
Abstract
We discuss the magnetic response of clean Ag coated Nb proximity cylinders in the temperature range 150 \mu K < T < 9 K. In the mesoscopic temperature regime, the normal metal-superconductor system shows the yet unexplained paramagnetic reentrant effect, discovered some years ago [P. Visani, A. C. Mota, and A. Pollini, Phys. Rev. Lett. 65, 1514 (1990)], superimposing on full Meissner screening. The logarithmic slope of the reentrant paramagnetic susceptibility chi_para(T) \propto \exp(-L/\xi_N) is limited by the condition \xi_N=n L, with \xi_N=\hbar v_F/2 \pi k_B T, the thermal coherence length and n=1,2,4. In wires with perimeters L=72 \mu m and L=130 \mu m, we observe integer multiples n=1,2,4. At the lowest temperatures, \chi_para compensates the diamagnetic susceptibility of the \textit{whole} AgNb structure.
Cite
@article{arxiv.cond-mat/9904344,
title = {Paramagnetic reentrant effect in high purity mesoscopic AgNb proximity structures},
author = {F. Bernd Mueller-Allinger and Ana Celia Mota},
journal= {arXiv preprint arXiv:cond-mat/9904344},
year = {2009}
}
Comments
4 pages, 4 figures (color)