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Charge transport and quantum phase transitions in singlet-superconductor/ferromagnet/singlet-superconductor junctions

Kastening, Boris and Morr, Dirk and Alff, Lambert and Bennemann, Karl (2009):
Charge transport and quantum phase transitions in singlet-superconductor/ferromagnet/singlet-superconductor junctions.
In: Physical Review B, pp. 144508-1-144508-14, 79, (14), ISSN 1098-0121, [Online-Edition: http://dx.doi.org/10.1103/PhysRevB.79.144508],
[Article]

Abstract

We study the Josephson current, IJ, in a junction consisting of two s-wave superconductors that are separated by a ferromagnetic barrier possessing magnetic and nonmagnetic scattering potentials, g and Z, respectively. We discuss the general dependence of IJ on g, Z, and the phase difference � between the two superconductors. Moreover, we compute the critical current, Ic, for given g and Z, and show that it possesses two lines of nonanalyticity 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 the 0 and � states of the junction. Finally, we show that by changing the relative phase �, 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 �Sz�=0 to �Sz�=1/ 2.

Item Type: Article
Erschienen: 2009
Creators: Kastening, Boris and Morr, Dirk and Alff, Lambert and Bennemann, Karl
Title: Charge transport and quantum phase transitions in singlet-superconductor/ferromagnet/singlet-superconductor junctions
Language: English
Abstract:

We study the Josephson current, IJ, in a junction consisting of two s-wave superconductors that are separated by a ferromagnetic barrier possessing magnetic and nonmagnetic scattering potentials, g and Z, respectively. We discuss the general dependence of IJ on g, Z, and the phase difference � between the two superconductors. Moreover, we compute the critical current, Ic, for given g and Z, and show that it possesses two lines of nonanalyticity 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 the 0 and � states of the junction. Finally, we show that by changing the relative phase �, 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 �Sz�=0 to �Sz�=1/ 2.

Journal or Publication Title: Physical Review B
Volume: 79
Number: 14
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Advanced Thin Film Technology
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 30 Mar 2012 08:12
Official URL: http://dx.doi.org/10.1103/PhysRevB.79.144508
Identification Number: doi:10.1103/PhysRevB.79.144508
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