Dominant Majorana bound energy and critical current enhancement in ferromagnetic-superconducting topological insulator

Abstract

Among the potential applications of topological insulators, we theoretically study the coexistence of proximity-induced ferromagnetic and superconducting orders in the surface states of a 3-dimensional topological insulator. The superconducting electron-hole excitations can be significantly affected by the magnetic order induced by a ferromagnet. In one hand, the surface state of the topological insulator, protected by the time-reversal symmetry, creates a spin-triplet and, on the other hand, magnetic order causes to renormalize the effective superconducting gap. We find Majorana mode energy along the ferromagnet/superconductor interface to sensitively depend on the magnitude of magnetization $m_{zfs}$ from superconductor region, and its slope around perpendicular incidence is steep with very low dependency on $m_{zfs}$. The superconducting effective gap is renormalized by a factor $\eta (m_{zfs})$, and Andreev bound state in ferromagnet-superconductor/ferromagnet/ferromagnet-superconductor (FS/F/FS) Josephson junction is more sensitive to the magnitude of magnetizations of FS and F regions. In particular, we show that the presence of $m_{zfs}$ has a noticeable impact on the gap opening in Andreev bound state, which occurs in finite angle of incidence. This directly results in zero-energy Andreev state being dominant. By introducing the proper form of corresponding Dirac spinors for FS electron-hole states, we find that via the inclusion of $m_{zfs}$, the Josephson supercurrent is enhanced and exhibits almost abrupt crossover curve, featuring the dominant zero-energy Majorana bound states.

Accepted, 11 pages, 6 figures, The European Physical Journal B 2017. arXiv admin note: substantial text overlap with arXiv:1701.08275

References in corpus (10)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Topological Insulators with Inversion Symmetry
• Non-Abelian Topological Order in S-Wave Superfluids of Ultracold Fermionic Atoms
• Electrically detected interferometry of Majorana fermions in a topological insulator
• Quantum Computation Using Vortices and Majorana Zero Modes of a $p_x$ + $i{p}_y$ Superfluid of Fermionic Cold Atoms
• Anomalous Transport through the p-Wave Superconducting Channel in the 3-K Phase of Sr2RuO4
• Majorana bound state in rotating superfluid 3He-A between parallel plates
• Josephson effect in normal and ferromagnetic topological insulator planar, step and edge junctions

Cited by in corpus (2)

• Asymmetric $d$-wave superconducting topological insulator in proximity with a magnetic order
• Asymmetric Andreev resonant state with a magnetic exchange field in spin-triplet superconducting monolayer $Mo{S}_2$