Comment on "Orbital Paramagnetism of Electrons in Proximity to a Superconductor"

Abstract

In a recent letter [Phys. Rev. Lett. 80, 5782 (1998)], Bruder and Imry address the reentrance effect in proximity coupled normal-metal coated superconducting cylinders discovered by Mota et al. and challenging theoretical understanding to date. At stake is the explanation of a low-temperature paramagnetic reentrance of order unity. The authors claim to find a `significant paramagnetic effect' which they strongly relate to the layout and findings of the experiment. Here, we show that the straightforward calculation of the paramagnetic change in the susceptibility along the lines of their analysis is by several orders of magnitude smaller than experimentally observed.