Giazotto, F. and Taddei, F. and Fazio, R. and Beltram, F. (2007) Nonequilibrium spin-dependent phenomena in mesoscopic superconductor-normal metal tunnel structures. Physical Review B 76, p. 184518.
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We analyze the broad range of spin-dependent nonequilibrium transport properties of hybrid systems composed of a normal region tunnel coupled to two superconductors with exchange fields induced by the proximity to thin ferromagnetic layers and highlight its functionalities. By calculating the quasiparticle distribution functions in the normal region, we find that they are spin dependent and strongly sensitive to the relative angle between exchange fields in the two superconductors. The impact of inelastic collisions on their properties is addressed. As a result, the electric current flowing through the system is found to be strongly dependent on the relative angle between exchange fields, giving rise to a huge value of magnetoresistance. Moreover, the current presents a complete spin polarization in a wide range of bias voltages, even in the quasiequilibrium case. In the nonequilibrium limit, we parametrize the distributions with an effective temperature, which turns out to be strongly spin dependent, though quite sensitive to inelastic collisions. By tunnel coupling the normal region to an additional superconducting electrode, we show that it is possible to implement a spin-polarized current source of both spin species, depending on the bias voltages applied.
|Institutions:||Physics > Institute of Theroretical Physics > Chair Professor Richter > Group Klaus Richter|
|Projects:||SPP 1243: Quantum transport at the molecular scale|
|Subjects:||500 Science > 530 Physics|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Deposited On:||25 May 2009 13:18|
|Last Modified:||07 Jul 2010 08:12|