采用线性化自旋量子流体动力学模型(Spin quantum hydrodynamic model SQHD)与Poisson方程相结合,研究了在外加磁场的作用下,电子自旋效应对带电粒子与双层二维电子气平面相互作用的影响。在适当的边界条件下,推导出两个平面内感应电子...采用线性化自旋量子流体动力学模型(Spin quantum hydrodynamic model SQHD)与Poisson方程相结合,研究了在外加磁场的作用下,电子自旋效应对带电粒子与双层二维电子气平面相互作用的影响。在适当的边界条件下,推导出两个平面内感应电子气密度、空间感应电势和感应电场对入射粒子的阻止力的一般表达式。结果表明,自旋效应对电子气密度分布和阻止力随速度变化均有一定的影响。在入射粒子附近,磁场使自旋向上的电子气密度振荡加强,而对自旋向下的电子气密度振荡起到抑制作用。由于两个电子气平面的相互耦合作用,阻止力随速度变化曲线出现了明显的双峰结构,随着入射磁场振幅和波数的增大,在速度较高的区域,无论电子自旋向上或向下,曲线均出现了明显的振荡衰减情况。展开更多
Through the Jordan Wigner transformation, the entanglement entropy and ground state phase diagrams of exactly solvable spin model with alternating and multiple spin exchange interactions are investigated by means of G...Through the Jordan Wigner transformation, the entanglement entropy and ground state phase diagrams of exactly solvable spin model with alternating and multiple spin exchange interactions are investigated by means of Green＇s function theory. In the absence of four-spin interactions, the ground state presents plentiful quantum phases due to the multiple spin interactions and magnetic fields. It is shown that the two-site entanglement entropy is a good indicator of quantum phase transition （QPT）. In addition, the alternating interactions can destroy the magnetization plateau and wash out the spin-gap of low-lying excitations. However, in the presence of four-spin interactions, apart from the second order QPTs, the system manifests the first order OPT at the tricritical point and an additional new phase called ＂spin waves＂, which is due to the collapse of the continuous tower-like low-lying excitations modulated by the four-spin interactions for large three-spin couplings.展开更多
By means of the Keldysh Green's function method,we investigate the spin-polarized electron transport in a three-terminal device,which is composed of three normal metal leads and two serially-coupled quantum dots(Q...By means of the Keldysh Green's function method,we investigate the spin-polarized electron transport in a three-terminal device,which is composed of three normal metal leads and two serially-coupled quantum dots(QDs).The Rashba spin-orbit interaction(RSOI) is also considered in one of the QDs.We show that the spin-polarized charge current with arbitrary spin polarization can be obtained because of the quantum spin interference effect arising from the Rashba spin precession phase,and it can be modulated by the system parameters such as the applied external voltages,the RSOI strength,the QD levels,as well as the dot-lead coupling strengths.Moreover,a fully spin-polarized current or a pure spin current without any accompanying charge current can also be controlled to flow in the system.Our findings indicate that the proposed model can serve as an all-electrical spin device in spintronics field.展开更多
All the possible CP-conserving non-linear operators up to the p^4-order in the Lagrangian expansion are analysed here for the left-right symmetric model in the non-linear electroweak chiral context coupled to a light ...All the possible CP-conserving non-linear operators up to the p^4-order in the Lagrangian expansion are analysed here for the left-right symmetric model in the non-linear electroweak chiral context coupled to a light dynamical Higgs. The low energy effects will be triggered by an emerging new physics field content in the nature, more specifically,from spin-1 resonances sourced by the straightforward extension of the SM local gauge symmetry to the larger local group SU(2)_L × SU(2)_R× U(1)_(B-L). Low energy phenomenology will be altered by integrating out the resonances from the physical spectrum, being manifested through induced corrections onto the left handed operators. Such modifications are weighted by powers of the scales ratio implied by the symmetries of the model and will determine the size of the effective operator basis to be used. The recently observed diboson excess around the invariant mass 1.8 TeV–2 TeV entails a scale suppression that suggests to encode the low energy effects via a much smaller set of effective operators.展开更多
文摘采用线性化自旋量子流体动力学模型(Spin quantum hydrodynamic model SQHD)与Poisson方程相结合,研究了在外加磁场的作用下,电子自旋效应对带电粒子与双层二维电子气平面相互作用的影响。在适当的边界条件下,推导出两个平面内感应电子气密度、空间感应电势和感应电场对入射粒子的阻止力的一般表达式。结果表明,自旋效应对电子气密度分布和阻止力随速度变化均有一定的影响。在入射粒子附近,磁场使自旋向上的电子气密度振荡加强,而对自旋向下的电子气密度振荡起到抑制作用。由于两个电子气平面的相互耦合作用,阻止力随速度变化曲线出现了明显的双峰结构,随着入射磁场振幅和波数的增大,在速度较高的区域,无论电子自旋向上或向下,曲线均出现了明显的振荡衰减情况。
基金Supported by the National Natural Science Foundation of China under Grant Nos.10774051 and 10804034the National 973 Project under Grant No.2006CB921605+1 种基金the Research Fund for the Doctoral Program of Higher Education under Grant No.20090142110063the National Science Foundation of Hubei Province of China under Grant No.2008CDB003
文摘Through the Jordan Wigner transformation, the entanglement entropy and ground state phase diagrams of exactly solvable spin model with alternating and multiple spin exchange interactions are investigated by means of Green＇s function theory. In the absence of four-spin interactions, the ground state presents plentiful quantum phases due to the multiple spin interactions and magnetic fields. It is shown that the two-site entanglement entropy is a good indicator of quantum phase transition （QPT）. In addition, the alternating interactions can destroy the magnetization plateau and wash out the spin-gap of low-lying excitations. However, in the presence of four-spin interactions, apart from the second order QPTs, the system manifests the first order OPT at the tricritical point and an additional new phase called ＂spin waves＂, which is due to the collapse of the continuous tower-like low-lying excitations modulated by the four-spin interactions for large three-spin couplings.
基金Supported by National Natural Science Foundation of China under Grant Nos. 10704016,110704032,110704033Natural Science Foundation of Jiangsu Province under Grant No. BK2010416National Basic Research Project of China under Grant No. 2009CB945504
文摘By means of the Keldysh Green's function method,we investigate the spin-polarized electron transport in a three-terminal device,which is composed of three normal metal leads and two serially-coupled quantum dots(QDs).The Rashba spin-orbit interaction(RSOI) is also considered in one of the QDs.We show that the spin-polarized charge current with arbitrary spin polarization can be obtained because of the quantum spin interference effect arising from the Rashba spin precession phase,and it can be modulated by the system parameters such as the applied external voltages,the RSOI strength,the QD levels,as well as the dot-lead coupling strengths.Moreover,a fully spin-polarized current or a pure spin current without any accompanying charge current can also be controlled to flow in the system.Our findings indicate that the proposed model can serve as an all-electrical spin device in spintronics field.
基金KITPC financial support during the completion of this work
文摘All the possible CP-conserving non-linear operators up to the p^4-order in the Lagrangian expansion are analysed here for the left-right symmetric model in the non-linear electroweak chiral context coupled to a light dynamical Higgs. The low energy effects will be triggered by an emerging new physics field content in the nature, more specifically,from spin-1 resonances sourced by the straightforward extension of the SM local gauge symmetry to the larger local group SU(2)_L × SU(2)_R× U(1)_(B-L). Low energy phenomenology will be altered by integrating out the resonances from the physical spectrum, being manifested through induced corrections onto the left handed operators. Such modifications are weighted by powers of the scales ratio implied by the symmetries of the model and will determine the size of the effective operator basis to be used. The recently observed diboson excess around the invariant mass 1.8 TeV–2 TeV entails a scale suppression that suggests to encode the low energy effects via a much smaller set of effective operators.
