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Lim J.S.,University of the Balearic Islands | Crisan M.,Technical University of Cluj Napoca | Sanchez D.,University of the Balearic Islands | Sanchez D.,Institute Of Fisica Interdisciplinar I Of Sistemes Complexos Ifisc | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We consider a flux-threaded Aharonov-Bohm ring with an embedded quantum dot coupled to two normal leads. The local Rashba spin-orbit interaction acting on the dot electrons leads to a spin-dependent phase factor in addition to the Aharonov-Bohm phase caused by the external flux. Using the numerical renormalization-group method, we find a splitting of the Kondo resonance at the Fermi level which can be compensated by an external magnetic field. To fully understand the nature of this compensation effect, we perform a scaling analysis and derive an expression for the effective magnetic field. The analysis is based on a tight-binding model which leads to an effective Anderson model with a spin-dependent density of states for the transformed lead states. We find that the effective field originates from the combined effect of Rashba interaction and magnetic flux and that it contains important corrections due to electron-electron interactions. We show that the compensating field is an oscillatory function of both the spin-orbit and the Aharonov-Bohm phases. Moreover, the effective field never vanishes due to the particle-hole symmetry breaking independently of the gate voltage. © 2010 The American Physical Society. Source


Gelabert M.M.,University of the Balearic Islands | Serra L.,University of the Balearic Islands | Serra L.,Institute Of Fisica Interdisciplinar I Of Sistemes Complexos Ifisc | Sanchez D.,University of the Balearic Islands | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We investigate intersubband mixing effects in multichannel quantum wires in the presence of Rashba spin-orbit coupling and attached to two terminals. When the contacts are ferromagnetic and their magnetization direction is perpendicular to the Rashba field, the spin-transistor current is expected to depend in an oscillatory way on the Rashba coupling strength due to spin coherent oscillations of the traveling electrons. Nevertheless, we find that the presence of many propagating modes strongly influences the spin precession effect, leading to (i) a quenching of the oscillations and (ii) strongly irregular curves for high values of the Rashba coupling. We also observe that in the case of leads' magnetization parallel to the Rashba field, the conductance departs from a uniform value as the Rashba strength increases. We also discuss the Rashba interaction-induced current-polarization effects when the contacts are not magnetic and investigate how this mechanism is affected by the presence of several propagating channels. © 2010 The American Physical Society. Source

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