Asymmetric d -wave superconducting topological insulator in proximity with a magnetic order

Abstract

In the framework of the Dirac-Bogoliubov-de Gennes formalism, we investigate the transport properties in the surface of a 3-dimensional topological insulator-based hybrid structure, where the ferromagnetic and superconducting orders are simultaneously induced to the surface states via the proximity effect. The superconductor gap is taken to be spin-singlet ¦ -wave symmetry. The asymmetric role of this gap respect to the electron-hole exchange, in one hand, affects the topological insulator superconducting binding excitations and, on the other hand, gives rise to forming distinct Majorana bound states at the ferromagnet/superconductor interface. We propose a topological insulator N/F/FS junction and proceed to clarify the role of ¦ -wave asymmetry pairing in the resulting subgap and overgap tunneling conductance. The perpendicular component of magnetizations in F and FS regions can be at the parallel and antiparallel configurations leading to capture the experimentally important magnetoresistance (MR) of junction. It is found that the zero-bias conductance is strongly sensitive to the magnitude of magnetization in FS region § © and orbital rotated angle of superconductor gap. The negative MR only occurs in zero orbital rotated angle. This result can pave the way to distinguish the unconventional superconducting state in the relating topological insulator hybrid structures.

Theory of the Josephson current on a magnetically doped topological insulator

“…A possible alternative to the FI/SC junction is a superconducting junction on a magnetically doped TI. There are several theoretical works on systems with coexisting magnetization and superconducting pairing in the same spatial region 14,[26][27][28][29] . Chiral Majorana modes are predicted to appear in such systems.…”

Mass-like band-gap creation in superconducting topological insulator due to mixed singlet and triplet states

“…We try to show the possible topological property of band structure. Specifically, electron-hole conversion at the normal metal-superconductor (NS) interface, so-called Andreev reflection (AR), and appearance of chiral Majorana state at the ferromagnet-superconductor (FS) interface can be considered as essential phenomena, which is directly influenced by the interplay between the spin-singlet and spin-triplet states in 3DTI [31][32][33]. In light of the above attributes, further treatment to study mixed-state 3DTI can be more impressive to evaluate its dynamical and transport properties.…”

Spin transport properties in ferromagnet/superconductor junctions on topological insulator

“…On the other hand, the transport properties in topological insulator (TI)-based superconducting junctions have also attracted great interests due to the peculiar band structures of TI. [10][11][12][13][14][15][16][17][18][19][20] For example, the tunneling conductance in TI-based FM/SC junctions is studied in order to investigate the effect of both the magneto and Fermi energy mismatch between FM and SC. [16] The interplay between unconventional SC and ferromagnetism in TI-based superconducting junctions is studied in Refs.…”