Fig. 1: Concept of interface spin polarization generation and detection in a planar Josephson junction.
From: Phase biasing of a Josephson junction using Rashba–Edelstein effect
a A schematic representation of the slitting of bias current in a Pt/Cu bilayer injected through Nb electrodes in the normal state of Nb. The total injected normal current, in this case, can be represented as a sum of the currents carried by the Pt layer (JPt), the Cu layers (JCu)and the Pt/Cu interface (JInt). We have represented the Pt/Cu interface as a separate layer as the current at the interface produces a non-equilibrium spin moment MRE due to the Rashba–Edelstein effect. Current through the heavy metal Pt layer generates spin polarization in a transverse direction by the spin hall effect. b When the same device is cooled to a temperature below the transition temperature of Nb electrodes (T < Tc), and a Josephson coupling is established between them, then the entire injected current is carried by the proximatized Cu layer. However, at the Pt/Cu interface, pair breaking by the spin-orbit coupling effects allows for some quasiparticle current JQ. The Pt/Cu Rashba interface creates an in-plane spin polarization MRE due to the quasiparticle current JQ. c The band representation of current driven shift of the momentum locked up-spin and down-spin bands causing a spin asymmetry at the Fermi surface. This causes the non-equilibrium spin moment depicted as MRE in panel (a, b). d In the presence of an external magnetic field the spin moment attains a component along the field which can couple into the junction area.
