Spin and charge persistent currents in a Kane Meleα-T₃quantum ring.

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Materials Science

Background:

• Spin-orbit coupling (SOC) is crucial in 2D quantum structures, affecting electronic properties.
• The α-T3 model provides a tunable platform interpolating between graphene and dice lattices.
• Persistent currents in quantum rings are sensitive to magnetic fields and material parameters.

Purpose of the Study:

• Investigate persistent charge and spin currents in a spin-orbit coupled α-T3 fermionic quantum ring.
• Analyze the distinct effects of intrinsic spin-orbit coupling (ISOC) and Rashba spin-orbit coupling (RSOC).
• Explore the influence of the α parameter, bridging graphene and dice lattice characteristics.

Main Methods:

• Theoretical modeling of a quantum ring with tunable α parameter and spin-orbit couplings.
• Analysis of energy levels, including conduction, valence, and flat bands, as a function of ring radius and magnetic field.
• Computation of charge and spin-polarized persistent currents under varying magnetic fields and SOC strengths.

Main Results:

• Energy levels exhibit non-monotonic dependence on ring radius (1/R for small R, linear for large R).
• Flat bands contribute to transport only with finite ISOC; RSOC induces spin-split bands.
• Persistent currents oscillate with magnetic flux quantum, with profiles modified by ISOC and preserved by RSOC.

Conclusions:

• Both ISOC and RSOC significantly modify persistent currents in the α-T3 quantum ring.
• ISOC distorts current profiles by affecting flat band distribution, while RSOC maintains current periodicity.
• The α parameter allows continuous tuning of electronic and transport properties between graphene and dice lattice limits.