Persistent charge and spin currents in a quantum ring using Green׳s function technique: Interplay between magnetic flux and spin–orbit interactions

• A new approach based on Green׳s function formalism is given to determine persistent currents.
• Like conventional methods, evaluations of eigenvalues and eigenfunctions are not required.
• Magnetic properties of large molecular rings encountered in biopolymers can be investigated.
• Persistent currents in large size rings can be determined with a very high degree of accuracy.

We put forward a new approach based on Green׳s function formalism to evaluate precisely persistent charge and spin currents in an Aharonov–Bohm ring subjected to Rashba and Dresselhaus spin–orbit interactions. Unlike conventional methods our present scheme circumvents direct evaluation of eigenvalues and eigenstates of the system Hamiltonian to determine persistent currents which essentially reduces possible numerical errors, especially for larger rings. The interplay of Aharonov–Bohm flux and spin–orbit interactions in persistent charge and spin currents of quantum rings is analyzed in detail and our results lead to a possibility of estimating the strength of any one of the spin–orbit fields provided the other one is known. All these features are exactly invariant even in the presence of impurities, and therefore, can be substantiated experimentally.

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