Time-dependent behavior of two kinds of arrays of two coupled quantum-dot cells is examined.Each square cell composed of four quantum dots in the corners contains two electrons and couples with the neighboring cells b...Time-dependent behavior of two kinds of arrays of two coupled quantum-dot cells is examined.Each square cell composed of four quantum dots in the corners contains two electrons and couples with the neighboring cells by Coulomb interactions.The electrons in one cell tend to occupy antipodal dots which results in a cell apolarizationtf.We have investigated the temporal evolution of the polarization of one cell under switch of the polarization of the other cell.Our results demonstrate that,with an adiabatic switch,if two cells are arranged in a line their polarizations will align each other,and if they are arranged in a diagonal way their polarizations will invert each other.However,with an abrupt switch,the above/features for the polarizations of two cells can not hold.The reason is that the system does not stay in its ground state.It is pointed out that the energy dissipation should be considered in order to obtain the appropriate solutions.展开更多
Self-consistent calculation of the electronic structure of quantum wires are implemented with an in-plane magnetic field parallel to the wire and spin-density-functional theory of Kohn and Sham is applied[Phys.Rev.A 1...Self-consistent calculation of the electronic structure of quantum wires are implemented with an in-plane magnetic field parallel to the wire and spin-density-functional theory of Kohn and Sham is applied[Phys.Rev.A 140(1965)1133].The self-consistent results show that full spontaneous spin polarization takes place in low electron density regime,even at an arbitrary small magnetic field,which demonstrates that the polarization is caused by exchange interactions.The results are consistent with recent measurements of a conductance anomaly in a quantum point contact.Moreover,it is remarkable that a large splitting of spin-related subbands occurs repeatedly whenever the Fermi energy passes the subband threshold energies,although the amplitude of the splitting becomes weaker as more subbands are occupied due to the screen effect.Self-consistent results indicate that a moderate magnetic field tends to suppress the spin polarization caused by the exchange interaction.The diamagnetic shift of the subbands is determined only for those which are close to the Fermi energy.展开更多
基金Supported by Shandong Distinguished Middle-aged and Young Scientist Encourage and Reward Foundation of China。
文摘Time-dependent behavior of two kinds of arrays of two coupled quantum-dot cells is examined.Each square cell composed of four quantum dots in the corners contains two electrons and couples with the neighboring cells by Coulomb interactions.The electrons in one cell tend to occupy antipodal dots which results in a cell apolarizationtf.We have investigated the temporal evolution of the polarization of one cell under switch of the polarization of the other cell.Our results demonstrate that,with an adiabatic switch,if two cells are arranged in a line their polarizations will align each other,and if they are arranged in a diagonal way their polarizations will invert each other.However,with an abrupt switch,the above/features for the polarizations of two cells can not hold.The reason is that the system does not stay in its ground state.It is pointed out that the energy dissipation should be considered in order to obtain the appropriate solutions.
基金Supported by the Shandong Distinguished Middle-AgedYoung Scientist EncourageReward Foundation of China.
文摘Self-consistent calculation of the electronic structure of quantum wires are implemented with an in-plane magnetic field parallel to the wire and spin-density-functional theory of Kohn and Sham is applied[Phys.Rev.A 140(1965)1133].The self-consistent results show that full spontaneous spin polarization takes place in low electron density regime,even at an arbitrary small magnetic field,which demonstrates that the polarization is caused by exchange interactions.The results are consistent with recent measurements of a conductance anomaly in a quantum point contact.Moreover,it is remarkable that a large splitting of spin-related subbands occurs repeatedly whenever the Fermi energy passes the subband threshold energies,although the amplitude of the splitting becomes weaker as more subbands are occupied due to the screen effect.Self-consistent results indicate that a moderate magnetic field tends to suppress the spin polarization caused by the exchange interaction.The diamagnetic shift of the subbands is determined only for those which are close to the Fermi energy.
