Spin selectivity induced by non-collinear spins in Rashba wires

We report a previously overlooked general mechanism to obtain highly efficient spin selectivity in conventional time-reversal symmetric one-dimensional systems without invoking phase decoherence. We reveal that Rashba quantum wires featuring non-collinear spin states at the Fermi level inherently possess spin-selective transport properties. We show that this spin noncollinearity can be systematically designed and engineered by introducing an additional pseudospin degree of freedom - such as valley, sublattice, or orbital angular momentum - into spin-orbit coupled systems. By applying this framework to multi-subband semiconducting quantum wires and oxide nanowires, we establish a generalized route toward quantum-coherent spin selectivity up to 10 %. Our findings offer practical design principles for spin-selective transport devices.