Spin-orbit interactions, time-reversal symmetry, and spin selection

Area of Science:

• Condensed matter physics
• Quantum transport

Background:

• Spin-selective transport is commonly linked to spin-orbit interactions.
• Standard theories (Onsager relations, Bardarson's theorem) preclude spin selectivity via time-reversal invariant interactions in simple junctions.
• Overcoming these limitations is crucial for spintronic applications.

Purpose of the Study:

• To review methods for achieving spin-selective transport beyond conventional spin-orbit interactions.
• To explore mechanisms that circumvent time-reversal symmetry constraints on spin selectivity.
• To identify potential connections with chiral-induced spin selectivity.

Main Methods:

• Review of theoretical approaches for spin-selective electron transport.
• Analysis of systems incorporating Zeeman magnetic fields.
• Consideration of Aharonov-Bohm phase effects.
• Investigation of time-dependent electric fields and transients.
• Examination of multi-terminal geometries and leakage effects.
• Study of junctions with multi-level ions.

Main Results:

• Demonstration that spin selectivity can be achieved without relying solely on static spin-orbit interactions.
• Identification of several distinct physical mechanisms that enable spin-polarized currents.
• Analysis of low-temperature, noninteracting electron transport scenarios.
• Highlighting a potential link to chiral-induced spin selectivity in specific configurations.

Conclusions:

• Novel strategies exist to engineer spin-selective transport, expanding beyond traditional spin-orbit coupling.
• The reviewed methods offer pathways to control spin currents in mesoscopic systems.
• Further research into these phenomena could advance spintronics and quantum information technologies.