Physical Review X (Aug 2014)
Orbital Ferromagnetism in Interacting Few-Electron Dots with Strong Spin-Orbit Coupling
Abstract
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 λλ_{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→∞.