Rashba spin2orbit coupling effect on tunneling time in semiconductor spintronic junctions S. M. Mirzanian • A. A. Shokri • S. M. Elahi Received: 29 June 2013 / Accepted: 13 August 2013 / Published online: 31 August 2013 Ó Springer Science+Business Media New York 2013 Abstract Based on the transfer-matrix method and the group velocity concept, we investigate theoretically the spin tunneling time through single and double barriers of diluted magnetic semiconductor structures in the presence of the Rashba spin-orbit coupling (RSOC) effect. The calculation of transmission probability is based on an effective mass quantum-mechanical approach in the pres- ence of an external magnetic field applied along the growth direction of the junction. The results show that the RSOC has great different influence on spin-dependent tunneling time of electrons with spin up and spin down in these structures. We also study the effect of zero-field conduction band offset on spin-dependent transmission properties. It is found that in the presence of RSOC and a positive zero- field conduction band offset as high as 10 meV, the results show a high degree of spin polarization and spin separation in the tunneling time in the considered system and this aspect may be utilized in designing new spin filter devices. Introduction Recently, there has been a great deal of attention in the field of spintronics, which involves the study of active control and manipulation of electron spin and charge degrees of freedom. The spin of electrons has a long dephasing time and a large phase coherent length [1– 3]. Therefore, the study of the injection, accumulation, polarization, screen- ing, and local properties of charge and spin help a better understanding of the relevant physics to design spintronic- based electronic devices [4, 5]. Spin-polarized transport through II–VI diluted magnetic semiconductor/non- magnetic semiconductor (DMS/NMS) barrier structures widely use in the spintronics due to their spin-dependent sp– d exchange interaction between the carriers and the local magnetic ions [6–12]. Egues [6] and Guo et al. [12] have investigated the spin filtering in a ZnSe/Zn 1-x Mn x hetero- structure with a single and double paramagnetic layers and found a strong suppression of the spin up component of current density at higher magnetic fields. The time scale of tunneling in mesoscopic nanostruc- tures has specifically attracted much of the efforts [13–17], because spin tunneling time is an important concept for ultimate performance evaluations of kinds of spintronics devices. Guo et al. [13–15] studied characteristics of spin tunneling time in ZnSe/ZnMnSe multilayers. They found that the tunneling time for electrons strongly depends on their spin orientation. Saffarzadeh and Daqiq [18] investi- gated how the geometry and the quantum size of the device affect the spin tunneling time and the degree of spin polarization of tunneling electrons in a (Zn,Mn)Se-based magnetic resonant tunneling diode. The effect of Rashba spin-orbit coupling (RSOC) is another spin-dependent potential which has been the focus of much research in the past decade both experimentally and theoretically [19–22]. Gui et al. [19] have investigated experimentally the gate voltage and temperature-dependent Shubnikov-de Haas oscillations in HgMnTe/HgCdTe het- erostructure. Their results demonstrated that the Rashba spin-orbit splitting is larger than or comparable to the sp– d exchange interaction. Zhang et al. [23] studied the effect of Rashba spin-orbit interaction on the traversal time of S. M. Mirzanian (&)  S. M. Elahi Plasma Physics Research Center, Science and Research Branch, Islamic Azad university, Tehran, Iran e-mail: m.mirzanian@srbiau.ac.ir A. A. Shokri Department of Physics, Payame Noor University, P. O. Box 19395-3697, Tehran, Iran 123 J Mater Sci (2014) 49:88–93 DOI 10.1007/s10853-013-7677-y