Charge Transport and Quantum Phase Transitions in Singlet Superconductor - Ferromagnet - Singlet Superconductor Junctions
Abstract
We study the Josephson current, I_J, in a junction consisting of two s-wave superconductors that are separated by a ferromagnetic barrier possessing a magnetic and non-magnetic scattering potential, g and Z, respectively. We discuss the general dependence of I_J on g, Z, and the phase difference \phi between the two superconductors. Moreover, we compute the critical current, I_c for given g and Z, and show that it possesses two lines of non-analyticity in the (g, Z)-plane. We identify those regions in the (g, Z)-plane where the Josephson current changes sign with increasing temperature without a change in the relative phase between the two superconductors, i.e., without a transition between a 0 and \pi state of the junction. Finally, we show that by changing the relative phase \phi, it is possible to tune the junction through a first-order quantum phase transition in which the spin polarization of the two superconductors' combined ground state changes from < S_z > =0 to < S_z > =1/2.
Keywords
Cite
@article{arxiv.cond-mat/0610283,
title = {Charge Transport and Quantum Phase Transitions in Singlet Superconductor - Ferromagnet - Singlet Superconductor Junctions},
author = {Boris Kastening and Dirk K. Morr and Lambert Alff and Karl Bennemann},
journal= {arXiv preprint arXiv:cond-mat/0610283},
year = {2009}
}
Comments
final version, published in Phys. Rev. B