Orbital Ferromagnetism in Interacting Few-Electron Dots with Strong Spin-Orbit Coupling

• Main Authors: Amin Naseri, Alex Zazunov, Reinhold Egger
• Format: Article
• Language: English
• Published: American Physical Society 2014-08-01
• Series: Physical Review X
• Online Access: http://doi.org/10.1103/PhysRevX.4.031033

We study the ground state of N weakly interacting electrons (with N≤10) in a two-dimensional parabolic quantum dot with strong Rashba spin-orbit coupling. Using dimensionless parameters for the Coulomb interaction λ≲1 and the Rashba coupling α≫1, the low-energy physics is characterized by an almost flat single-particle dispersion. From an analytical approach for α→∞ and N=2, and from numerical exact-diagonalization and Hartree-Fock calculations, we find a transition from a conventional unmagnetized ground state (for λ<λ_{c}) to an orbital ferromagnet (for λ>λ_{c}), with a large magnetization and a circulating charge current. We show that the critical interaction strength λ_{c}=λ_{c}(α,N) vanishes in the limit α→∞.