Jacob Linder

Unconventional superconductivity on a topological insulator.

We study proximity-induced superconductivity on the surface of a topological insulator (TI), focusing on unconventional pairing. We find that the excitation spectrum becomes gapless for any spin-triplet pairing, such that both subgap bound states and Andreev reflection is strongly suppressed. For spin-singlet pairing, the zero-energy surface state in the d(xy)-wave case becomes a Majorana fermion, in contrast with the situation realized in the topologically trivial high-T(c) cuprates. We also study the influence of a Zeeman field on the surface states. Both the magnitude and direction of this field are shown to strongly influence the transport properties, in contrast with the case without TI. We predict an experimental signature of the Majorana states via conductance spectroscopy.

Anomalous finite size effects on surface states in the topological insulator Bi 2 Se 3

We study how the surface states in the strong topological insulator

Tunneling conductance in s-and d-wave superconductor-graphene junctions : Extended Blonder-Tinkham-Klapwijk formalism

{\text{Bi}}_{2}{\text{Se}}_{3}

Interplay between superconductivity and ferromagnetism on a topological insulator

are influenced by finite size effects and compare our results with those recently obtained for two-dimensional topological insulator HgTe. We demonstrate two important distinctions: (i) contrary to HgTe, the surface states in

Signature of magnetic-dependent gapless odd frequency states at superconductor/ferromagnet interfaces

{\text{Bi}}_{2}{\text{Se}}_{3}

Pairing symmetry conversion by spin-active interfaces in magnetic normal-metal-superconductor junctions.

display a remarkable robustness towards decreasing the width

Supercurrent switch in graphene pi junctions.

L

Anomalous magnetic transport in ferromagnetic graphene junctions

down to a few nm thus ensuring that the topological surface states remain intact and (ii) the gapping due to the hybridization of the surface states features an oscillating exponential decay as a function of

General boundary conditions for quasiclassical theory of superconductivity in the diffusive limit: Application to strongly spin-polarized systems

L

Josephson current in graphene: Role of unconventional pairing symmetries

in