Susceptibility Of Quantum Dots Research Articles

Magnetic properties in three electrons under Rashba spin‐orbit interaction and magnetic field

AbstractIn this work, we study three‐electron magnetic susceptibility in quantum dots under Rashba spin‐orbit interaction (SOI) and magnetic field by an analytical methodology. The Hamiltonian of the system is separated to center of mass and relative terms using the Jacobi transformations and the hyperspherical coordinates. By solving Schrodinger equation, energy levels and thereby the susceptibility are calculated using canonical ensemble. At zero temperature, the magnetization reduces with increasing magnetic field with and without Rashba SOI in three‐electron‐quantum dot without electron‐electron (e‐e) interaction. Also, SOI slightly changes the magnetization for three‐electron‐quantum dot without e‐e interaction. At nonzero temperature, the magnetization shows a paramagnetic peak when the magnetic field increases. This peak position changes under the SOI. In the presence of e‐e interaction, the susceptibility enhances with raising magnetic field and it shows a maximum. The susceptibility at low magnetic field is negative and then it becomes positive. The susceptibility with e‐e interaction and without SOI is always diamagnetic and its magnitude reduces with enhancing magnetic field. The susceptibility shows a transition between diamagnetic and paramagnetic with e‐e interaction and SOI.

Simultaneous effects of electron-electron interactions, Rashba spin-orbit interaction and magnetic field on susceptibility of quantum dots

In this work, we have theoretically studied susceptibility of an InAs quantum dot in the presence of Rashba spin–orbit interaction (SOI), electron-electron (e−-e−) interaction, and magnetic field. We have used two potential models, shifted parabolic and inverse lateral shifted parabolic potentials. We have first solved the Schrodinger equation to obtain energy levels and then obtain the susceptibility using canonical ensemble. It is found that the susceptibility at low magnetic field is negative and then it becomes positive with increasing the magnetic field. This transition occurs at a particular magnetic field. The transition diamagnetism to paramagnetism occurs at lower magnetic field when the temperature increases. The susceptibility reduces with increasing temperature without considering the Rashba SOI. With considering e−-e− interaction, the peak position of susceptibility shifts toward lower magnetic fields. Also, the temperature has an effect on width and height of susceptibility.

Second-order nonlinear susceptibility in quantum dot structure under applied electric field

A model for quantum dot (QD) subbands, when the dots are in the form of quantum disks, under applied electric field was stated. Then, subbands of dots with different disk radii and heights were calculated under applied field. The competition between the shift due to confinement by field and the size was shown for subbands. Second-order nonlinear susceptibility in quantum dots (QDs) was derived using density matrix theory which is, then, simulated using the calculated subbands. Both interband (IB) and intersubband (ISB) transitions were discussed. High second-order susceptibility in QDs was predicted. The results show a reduction in the susceptibility with the applied field while the peak wavelength was mainly relates to energy difference between subbands. A good match between theory and laboratory experiments was observed. Laboratory experiments at terahertz region might be possible using valence intersubband which is important in many device applications.