Quantum transport in two dimensional electron gas/p-wave superconductor junction with Rashba spin–orbit coupling at the interface and in the normal layer R. Mohammadkhani n , Gh. Hassanloo Department of Physics, Faculty of Sciences, University of Zanjan, Zanjan 45371-38791, Iran article info Article history: Received 10 December 2013 Received in revised form 4 June 2014 Accepted 30 June 2014 Available online 8 July 2014 Keywords: Josephson junction Superconductor Conductance Rashba spin–orbit coupling BTK formalism Tunneling spectroscopy abstract We have studied the tunneling conductance of a clean two dimensional electron gas/p- wave superconductor junction with Rashba spin–orbit coupling (RSOC) which is present in the normal layer and at the interface. Using the extended Blonder–Tinkham–Klapwijk formalism we have found that the subgap conductance peaks are shifted to a nonzero bias by RSOC at the interface which are the same as Ref. [1]. It is shown that for low insulating barrier and in the absence of the interface RSOC, the tunneling conductance decreases within energy gap with increasing of the RSOC in the normal layer while for high insulating barrier it enhances by increase of the RSOC. We have also shown that the RSOC inside the normal cannot affect the location of the subgap conductance peaks shifted by the interface RSOC. & 2014 Elsevier B.V. All rights reserved. 1. Introduction Tunneling spectroscopy is one of the highest energy- resolution probes for the electronic states of superconductors. The several methods for investigating of the tunneling spectro- scopy have been proposed, but one of the most successful formulae to study it in a normal metal/superconductor (N/S) junction, with an arbitrary strength of the barrier at the interface has been presented by Blonder, Tinkham and Klapwijk (BTK) [2]. In this method, the conductance spectrum is described in terms of Andreev reflection (AR) [3] amplitudes at the interface. The AR is a process that an electron with up spin injected from N at the energy below the energy gap is converted into a reflected hole with down spin. The BTK theory has been extended to the ferromagnet/super- conductor (F/S) junctions and used to estimate the spin polarization of the F layer experimentally [4–6] and theoretically [7–12]. In FS junctions, AR is suppressed by the exchange field in the F layer, as a result, the conductance of the junctions is decreased. Spin dependent transport in FS junctions has attracted a considerable attention due to applications in spintronics [13] which aims to fabricate novel devices manipulating the spin of the electron. Spintronics has recently received much attention because of its potential on electric devices and quantum computing [14]. Among these works, many efforts have been devoted to study the effect of spin–orbit coupling on transport properties of two dimensional electron gas (2DEG) [15–17]. Datta and Das suggested the way to control the precession of the spins of electrons by the Rashba spin–orbit coupling (RSOC) [18] in F/2DEG/F junctions [19]. RSOC is controllable via an applied electric field and can be tuned by a gate voltage. Similar to the exchange field in FS junctions, the RSOC may affect the tunneling conductance in 2DEG/S junctions because the RSOC leads to an energy splitting which removes the spin degeneracy. But unlike an exchange splitting in a ferromagnet, the energy splitting by the RSOC does not break the time reversal symmetry. Therefore transport properties in 2DEG/S contacts may be qualitatively different from those in FS junctions. The BTK theory has been extended by Tanaka and Kashiwaya to include the anisotropy of the pair potential in d-wave super- conductors to reveal the surface electronic states [20,21]. Recently, the effects of unconventional d-wave and p-wave pairing and the exchange interaction in F/S systems, such as the zero-bias conductance peak and the virtual Andreev reflection, have been clarified by Kashiwaya et al. [22] and Yoshida et al. [23]. The Fermi velocity mismatch between two metals can also significantly affect the Andreev reflection by altering the subgap conductance [24] which is similar to the presence of an insulating barrier [25]. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/physb Physica B http://dx.doi.org/10.1016/j.physb.2014.06.041 0921-4526/& 2014 Elsevier B.V. All rights reserved. n Corresponding author. Tel.: þ98 24 3305 2544; fax.: þ98 24 3328 3203. E-mail address: rmkhani@znu.ac.ir (R. Mohammadkhani). Physica B 452 (2014) 46–54