We study the spin-dependent transport through a one-dimensional quantum ring with taking both the Rashba spin-orbit coupling （RSOC） and ferromagnetic leads into consideration. The linear conductance is obtained by the Green＇s function method. We find that due to the quantum interference effect arising from the RSOC-induced spin precession phase and the difference in travelling phase between the two arms of the ring, the conductance becomes spin-polarized even in the antiparallel magnetic configuration of the two leads, which is different from the case in single conduction channel system. The linear conductance, the spin polarization and the tunnel magnetoresistance are periodic functions of the two phases, and can be efficiently tuned by the structure parameters.
Spin-dependent electronic transport through a quantum dot coupled to one ferromagnetic lead and one normal metal lead is investigated by using the master equation approach.Both the intradot spin-flip transition and Coulomb interaction are studied for the current polarization p=（I_↑-I_↓）/（I_↑＋I_↓）.It is found that p is suppressed to zero for a particular regime of one direction bias,while it is enhanced to a relative maximum value when the bias is reversed, which is called the spin-current diode effect.The bias regime of this effect is determined by the dot level position and the intradot Coulomb interaction strength.We give a physical explanation and several control methods for it.This device is realizable with current nanofabrication technology and should have practical applications in spintronics.
We propose to generate and reverse the spin accumulation in a quantum dot （QD） by using the temperature difference between the two ferromagnetic leads connected to the dot. The electrons are driven purely by the temperature gradient in the absence of an electric bias and a magnetic field. In the Coulomb blockade regime, we find two ways to reverse the spin accumulation. One is by adjusting the QD energy level with a fixed temperature gradient, and the other is by reversing the temperature gradient direction for a fixed value of the dot level. The spin accumulation in the QD can be enhanced by the magnitudes of both the leads＇ spin polarization and the asymmetry of the dot-lead coupling strengths. The present device is quite simple, and the obtained results may have practical usage in spintronics or quantum information processing.
