Spin-orbit-induced chirality of Andreev states in Josephson junctions

A. A. REYNOSO; GONZALO USAJ; C. A. BALSEIRO; D. FEINBERG; M. AVIGNON

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2012 vol. 86 p. 214519 - 214519

1098-0121

We study Josephson junctions (JJs) in which the region between the two superconductors is a multichannel system with Rashba spin-orbit coupling (SOC) where a barrier or a quantum point contact (QPC) is present. These systems might present unconventional Josephson eects such as Josephson currents for zero phase dierence or critical currents that depend on the current direction. Here, we discuss how the spin polarizing properties of the system in the normal state aect the spin characteristic of the Andreev bound states inside the junction. This results in a strong correlation between the spin of the Andreev states and the direction in which they transport Cooper pairs. While the current phase relation for the JJ at zero magnetic field is qualitatively unchanged by SOC, in the presence of a weak magnetic field a strongly anisotropic behavior and the mentioned anomalous Josephson eects follow. We show that the situation is not restricted to barriers based on constrictions such as QPCs and should generically arise if in the normal system the direction of the carrier?s spin is linked to its direction of motion.