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Quantum rings in magnetic fields and spin current generation
Michele Cini1, Stefano Bellucci
1Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome, Italy. Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Frascati, Via E. Fermi 40, I-00044 Frascati, Italy.
Summary
We present three methods to generate spin-polarized currents in quantum rings using time-dependent magnetic fields. Two methods produce alternating currents without spin-orbit interaction, while the third generates a purely spin current with spin-orbit interaction.
Area of Science:
- Quantum physics
- Condensed matter physics
- Spintronics
Background:
- Spin-polarized currents are crucial for spintronics applications.
- Controlling spin currents in nanoscale devices is a key challenge.
- Quantum rings offer a platform for studying spin-dependent transport phenomena.
Purpose of the Study:
- To propose novel mechanisms for pumping spin-polarized currents in a ballistic quantum ring.
- To investigate the role of time-dependent magnetic fields and spin-orbit interaction in generating spin currents.
- To analytically and numerically demonstrate the feasibility of these pumping mechanisms.
Main Methods:
- Theoretical modeling of electron transport in a quantum ring.
- Application of time-dependent magnetic fields (rotating or in-plane).
- Analytical derivations and numerical simulations of charge and spin currents.
Main Results:
- A rotating magnetic field generates an alternating current with partial spin polarization.
- Rotating the quantum ring in a constant field produces an alternating charge current and a DC spin current.
- A purely spin current can be pumped using spin-orbit interaction and an in-plane time-dependent magnetic field.
Conclusions:
- Three distinct mechanisms for pumping spin-polarized currents in quantum rings are demonstrated.
- The proposed methods offer pathways to generate spin currents with or without spin-orbit interaction.
- The findings contribute to the development of spin-based electronic devices.
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