Off center $D^-$ centers in a quantum well in the presence of a perpendicular magnetic field: angular momentum transition and magnetic evaporation

TL;DR

This study explores how the position of a donor in a quantum well affects the energy states and magnetic field-induced transitions of a D- system, revealing off-center effects, singlet-triplet transitions, and unbinding phenomena.

Contribution

It demonstrates the impact of donor position on energy spectrum and magnetic transitions in D- centers within quantum wells, including the dependence on well width.

Findings

Off-center D- centers exhibit singlet-triplet transitions under magnetic fields.

The number of transitions depends on donor position and well width.

Large magnetic fields can unbind the two-electron system.

Abstract

We investigate the effect of the position of the donor in the quantum well on the energy spectrum and the oscillator strength of the D- system in the presence of a perpendicular magnetic field. As a function of the magnetic field we find that when the D- centers are placed sufficiently off-center they undergo singlet-triplet transitions which are similar to those found in many-electron parabolic quantum dots. The main difference is that the number of such transitions depends on the position of the donor and only a finite number of such singlet-triplet transitions are found as function of the strength of the magnetic field. For sufficiently large magnetic fields the two electron system becomes unbound. For the near center D- system no singlet-triplet and no unbinding of the D- is found with increasing magnetic field. A magnetic field vs. donor position phase diagram is presented that depends on the width of the quantum well.