Abstract
Spin textures of one or two electrons in a quantum dot with Rashba or Dresselhaus spin-orbit couplings reveal several intriguing properties. We show here that even at the single-electron level stable spin vortices with tunable topological charges exist. These topological textures appear in the ground state of the dots. The textures are stabilized by time-reversal symmetry breaking and are robust against the eccentricity of the dot. The topological charge is directly related to the sign of the z component of the spin in a large dot, allowing a direct probe of its topological properties. This would clearly pave the way to possible future topological spintronics. The phenomenon of spin vortices persists for the interacting two-electron dot in the presence of a magnetic field.
Highlights
Quantum dots (QDs) are of practical and fundamental interest and provide an excellent platform to control the spin and charge of a single electron[15,16,17]
We demonstrate that generic SOCs compel the spin field to rotate around the center of the QD and to develop into a spin vortex
The combination of electron confinement and SOCs leads to vortex-like spin textures in the ground state even for a single-electron dot
Summary
Quantum dots (QDs) are of practical and fundamental interest and provide an excellent platform to control the spin and charge of a single electron[15,16,17]. In quantum Hall systems the skyrmion is a single-particle excitation in low Landau levels and the in-plane spin texture is similar to the one we find in a QD with SOC. The rotational symmetry of the dot and the conservation of total angular momentum are at the heart of the meron-like spin textures observed in cylindrical dots with a large z component thickness in the presence of linear and cubic Dresselhaus SOCs38. The spin textures described in the following are stable and tunable, are neither skyrmions nor merons, and exist even without the rotational symmetry, at the single- and multi-electron level, and for any given magnetic field. We focus on the physics of the two-dimensional (2D) surface where the QD is constructed We consider both the Rashba and the linear Dresselhaus SOCs which arise in materials with broken inversion symmetry. We will show that this leads to a system where the topological charge can be dynamically controlled by external electromagnetic fields making spin vortices in QDs possible candidates for future applications in topological spintronics and quantum information
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