Effect of Rashba spin–orbit coupling, magnetization, and mixing of gap parameter on tunneling conductance in F∣NCSC junction of an F∣NCSC∣F spin valve

Abstract

In this paper, we study the quantum transport at the Ferromagnet|Noncentrosymmetric Superconductor (F|NCSC) interface of an F|S|F spin valve. In this context, we investigate the tunneling conductance and its dependence on Rashba Spin-Orbit Coupling (RSOC) considering different barrier strength and a significant Fermi Wave-vector Mismatch (FWM) at the ferromagnetic and superconducting regions. The study is carried out for different magnetization orientations and its strength. We developed Bogoliubov de Gennes (BdG) Hamiltonian introducing RSOC and exchange interaction for such an hybrid structure. To study charge conductance we use an extended Blonder -Tinkham -Klapwijk (BTK) approach along with scattering matrix formalism to calculate the scattering coefficients. Our results strongly suggest that the tunneling conductance is strongly dependent on RSOC, magnetization strength, its orientation and the FWM. The work has also been done for different singlet-triplet mixing of the gap parameter. We have observed that with the rise of singlet-triplet mixing ratio the conductance decreases. It is also observed that a transparent barrier with moderate RSOC and having moderate magnetization strength with arbitrary orientation is highly suitable for maximum conductance. PACS numbers: 67.30.hj, 74.90.+n

Signature of Anomalous Andreev bound states in magnetic Josephson junction of noncentrosymmetric superconductor on a topological insulator

“…The last term in the first square backet of Eq. ( 5) is the contribution due to the RSOC, with V R being the strength of the RSOC and it arises due to the asymmetry of the interface as well as due to NCSC [58][59][60][61][62].…”

“…Since both even and odd frequency correlations are present in NCSC at the same time, so the gap matrix ∆αβ appearing in Eq. ( 2) can be represented as a superposition of the singlet and triplet components [60][61][62], i.e.…”

“…The reasons for considering NCSC are: (i) Coexistence of spin-singlet and spin-triplet superconducting correlations and (ii) the existence of strong Antisymmetric Spin-Orbit Coupling (ASOC) due to the absence of inversion symmetry . Earlier studies indicate that due to the presence of the Rashba Spin-Orbit Coupling (RSOC) the pairing symmetry and hence the transport properties drastically get influenced in NCSC heterostructure [56][57][58][59][60][61][62]. Moreover, it is also reported that the RSOC and singlet-triplet mixing ratio of NCSC play very significant roles in the formation of ABS and supercurrent [72][73][74][75][76][77][78].…”

Spin transport and Spin Tunnelling Magneto-Resistance (STMR) of F|NCSC|F spin valve

“…Thus, in view of this the angularly averaged spin conductance can be written as [97,103,106,107,118]…”

“…In most of the earlier works on tunnelling spectroscopy [97][98][99][100][101][102][103][104][105][106][107][108][109], it was found that the barrier thickness play a very significant role on the transport mechanism. However, the role of barrier thickness on spin transport is yet to be understood.…”