Electronic structure of nuclear-spin-polarization-induced quantum dots

We study a system in which electrons in a two-dimensional electron gas are confined by a nonhomogeneous nuclear spin polarization. The system consists of a heterostructure that has non-zero nuclei spins. We show that in this system electrons can be confined into a dot region through a local nuclear spin polarization. The nuclear-spin-polarization-induced quantum dot has interesting properties indicating that electron energy levels are time-dependent because of the nuclear spin relaxation and diffusion processes. Electron confining potential is a solution of diffusion equation with relaxation. Experimental investigations of the time-dependence of electron energy levels will result in more information about nuclear spin interactions in solids

Bound states of L-shaped or T-shaped quantum wires in inhomogeneous magnetic fields

The bound state energies of L-shaped or T-shaped quantum wires in inhomogeous magnetic fields are found to depend strongly on the asymmetric parameter $\alpha =W_{2}/W_{1}$, i.e. the ratio of the arm widths. Two effects of magnetic field on bound state energies of the electron are obtained. One is the depletion effect which purges the electron out of the OQD system. The other is to create an effective potential due to quantized Landau levels of the magnetic field. The bound state energies of the electron in L-shaped or T-shaped quantum wires are found to depend quadratically (linearly) on the magnetic field in the weak (strong) field region and are independent of the direction of the magnetic field. A simple model is proposed to explain the behavior of the magnetic dependence of the bound state energy both in weak and strong magnetic field regions.Comment: 4 pages, 4 figure

Ring-shaped Andreev billiards in quantizing magnetic fields.

We present a detailed semiclassical study of a clean disk-shaped insulator–normal-metal–superconductor hybrid system in a magnetic field. It is based on an exact secular equation that we derived within the microscopic Bogoliubov–de Gennes (BdG) formalism. Results obtained from a classification of electron and hole orbits are in excellent agreement with those from an exact numerical diagonalization of the BdG equation. Our analysis opens up different possibilities for determining thermodynamic properties of mesoscopic hybrid systems