Unconventional superconductivity on a topological insulator (2009)
Linder, Jacob, Tanaka, Yukio, Yokoyama, Takehito, Sudbø, Asle, Nagaosa, Naoto
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-polarized Josephson current in SFS junctions with inhomogeneous magnetization (2009)
Alidoust, Mohammad, Linder, Jacob, Rashedi, Gholamreza, Yokoyama, Takehito, Sudbø, Asle
SHORTENED ABSTRACT: We study numerically the properties of spin- and charge-transport in a nanoscale diffusive superconductor$\mid$ferromagnet$\mid$superconductor junction when the magnetization...
Alidoust, Mohammad, Linder, Jacob, Rashedi, Gholamreza, Sudbø, Asle
We study the thermodynamic properties of a dirty ferromagnetic S$\mid$F$\mid$S Josephson junction with s-wave superconducting leads in the low-temperature regime. We employ a full numerical solution...
Anomalous Finite Size Effects on Surface States in the Topological Insulator Bi$_2$Se$_3$ (2009)
Linder, Jacob, Yokoyama, Takehito, Sudbø, Asle
We study how the surface states in the strong topological insulator Bi$_2$Se$_3$ are influenced by finite size effects, and compare our results with those recently obtained for 2D topological...
Probing phase-separation in Bose-Fermi mixtures by the critical superfluid velocity (2009)
We investigate the effect exerted by spin-polarized fermions on the interaction between superfluid bosons for a Bose-Fermi mixture residing on an optical lattice, with particular emphasis on the...
Sperstad, Iver Bakken, Linder, Jacob, Sudbø, Asle
We study quantum transport in ballistic $s_\pm$-wave superconductors where coupling between the two bands is included, and apply our model to three possible probes for detecting the internal phase...
Josephson current in graphene: the role of unconventional pairing symmetries (2009)
Linder, Jacob, Black-Schaffer, Annica M., Yokoyama, Takehito, Doniach, Sebastian, Sudbø, Asle
We investigate the Josephson current in a graphene superconductor/normal/superconductor junction, where superconductivity is induced by means of the proximity effect from external contacts. We take...
Crossed Andreev reflection in superconducting graphene spin-valves: Spin-switch effect (2009)
Linder, Jacob, Zareyan, Malek, Sudbø, Asle
We consider the non-local quantum transport properties of a graphene superconducting spin-valve. It is shown that one may create a spin-switch effect between perfect elastic co-tunneling (CT) and...
Reflection Induced Charge-Spin Current Separation (2009)
Linder, Jacob, Yokoyama, Takehito, Sudbø, Asle
The concept of a spin-current is a useful tool in understanding spin-transport in hybrid systems, but its very definition is problematic in systems where spin-orbit coupling effects are strong. We...
We investigate a model of a two-component Bose-Einstein condensate residing on an optical lattice. Within a Bogolioubov-approach at the mean-field level, we derive exact analytical expressions for...
Pairing symmetry conversion by spin-active interfaces in superconducting junctions (2009)
Linder, Jacob, Yokoyama, Takehito, Sudbø, Asle, Eschrig, Matthias
We study the proximity-induced superconducting correlations in a normal metal connected to a superconductor when the interface between them is spin-active and the normal metal is ballistic or...
Proximity effect in ferromagnet/superconductor hybrids: from diffusive to ballistic motion (2009)
Linder, Jacob, Zareyan, Malek, Sudbø, Asle
We present an analytical study of the proximity effect in ferromagnet/superconductor (F/S) heterostructures, allowing for an arbitrary magnetic exchange energy as well as arbitrary impurity and...
Linder, Jacob, Yokoyama, Takehito, Sudbø, Asle
We present a study of the proximity effect and the inverse proximity effect in a superconductor$\mid$ferromagnet bilayer, taking into account several important factors which mostly have been ignored...
Linder, Jacob, Sperstad, Iver B., Sudbø, Asle
We investigate the Josephson coupling properties of the superconducting ferropnictides in the experimentally relevant diffusive limit. In particular, we focus on the proposed $s_\pm$-wave state and...
Silaev, Mihail A., Yokoyama, Takehito, Linder, Jacob, Tanaka, Yukio, Sudb\o, Asle
We consider different effects that arise when time-reversal symmetry breaking superconductors are subjected to an external magnetic field, thus rendering the superconductor to be in the mixed state....
Quantum transport and proximity effects in unconventional superconducting hybrid systems (2009)
This thesis presents some of the main findings from twenty-five research articles. These papers may roughly be categorized into three fields: i) Proximity structures of superconductors and...
Quantum transport and proximity effects in unconventional superconducting hybrid systems (2009)
This thesis presents some of the main findings from twenty-five research articles. These papers may roughly be categorized into three fields: i) Proximity structures of superconductors and...
Theory of Andreev reflection in junctions with iron-based High-$T_c$ superconductors (2008)
We construct a theory for low-energy quantum transport in normal$\mid$superconductor junctions involving the recently discovered iron-based high-$T_c$ superconductors. We properly take into account...
Linder, Jacob, Nevidomskyy, Andriy H., Sudbø, Asle
Motivated by the recent discoveries of ferromagnetic and non-centrosymmetric superconductors, we present a mean-field theory for a superconductor that \textit{both} lacks inversion symmetry and...
We calculate the density of states (DOS) in a diffusive superconducting/ferromagnetic bilayer with a spin-active interface. We use a self-consistent numerical treatment to make a systematic study of...
Josephson current in diffusive multilayer superconductor/ferromagnet/superconductor junctions (2008)
Sperstad, Iver B., Linder, Jacob, Sudbø, Asle
We calculate the Josephson current in a diffusive superconductor/ferromagnet/superconductor junction, where the ferromagnetic region contains multiple layers (or domains). In particular, we study a...
Linder, Jacob, Yokoyama, Takehito, Sudbø, Asle
We investigate numerically the local density of states (LDOS) in the vicinity of a vortex core in a ferromagnetic superconductor. Specifically, we investigate how the LDOS is affected by the relative...
Strongly spin-polarized current generated in a Zeeman-split unconventional superconductor (2008)
Linder, Jacob, Yokoyama, Takehito, Tanaka, Yukio, Sudbø, Asle
We consider a thin-film normal- metal/superconductor junction in the presence of an externally applied in-plane magnetic field for several symmetries of the superconducting order parameter. For...
Strongly spin-polarized current generated in Zeeman-split unconventional superconductors (2008)
Linder, Jacob, Yokoyama, Takehito, Tanaka, Yukio, Sudbø, Asle
We consider a thin-film normal metal/superconductor junction in the presence of an externally applied in-plane magnetic field for several symmetries of the superconducting order parameter. For p-wave...
Linder, Jacob, Yokoyama, Takehito, Sudb\o, Asle
We present a numerical study of the density of states in a ferromagnet/superconductor junction and the Josephson current in a superconductor/ferromagnet/superconductor junction in the diffusive limit...
Quantum transport in a normal metal/odd-frequency superconductor junction (2008)
Linder, Jacob, Yokoyama, Takehito, Tanaka, Yukio, Asano, Yasuhiro, Sudbø, Asle
Recent experimental results indicate the possible realization of a bulk odd-frequency superconducting state in the compounds CeCu_2Si_2 and CeRhIn_5. Motivated by this, we present a study of the...
Linder, Jacob, Sperstad, Iver B., Nevidomskyy, Andriy, Cuoco, Mario, Sudb\o, Asle
We construct a mean-field theory for itinerant ferromagnetism coexisting with a non-unitary superconducting state, where only the majority-spin band is gapped and contains line nodes, while the...
A supercurrent switch in graphene $\pi$-junctions (2008)
Linder, Jacob, Yokoyama, Takehito, Huertas-Hernando, Daniel, Sudb\o, Asle
We study the supercurrent in a superconductor/ferromagnet/superconductor graphene junction. In contrast to its metallic counterpart, the oscillating critical current in our setup decays only weakly...
Heat transport by Dirac fermions in normal/superconducting graphene junctions (2008)
Yokoyama, Takehito, Linder, Jacob, Sudbo, Asle
We study heat transport in normal/superconducting graphene junctions. We find that while the thermal conductance displays the usual exponential dependence on temperature, reflecting the s-wave...
We investigate the conductance spectra of a normal/superconductor graphene junction using the extended Blonder-Tinkham-Klapwijk formalism, considering pairing potentials that are both conventional...
Quantum transport in a normal metal/odd-frequency superconductor junction (2007)
Linder, Jacob, Yokoyama, Takehito, Tanaka, Yukio, Asano, Yasuhiro, Sudb\o, Asle
Recent experimental results indicate the possible realization of a bulk odd-frequency superconducting state in the compounds CeCu$_2$Si$_2$, and CeRhIn$_5$. Motivated by this, we present a study of...
Identifying the odd-frequency superconducting state by a field-induced Josephson effect (2007)
Linder, Jacob, Yokoyama, Takehito, Sudb\o, Asle
Superconducting order parameters that are odd under exchange of time-coordinates of the electrons constituting a Cooper-pair, are potentially of great importance both conceptually and...
Spin-flip scattering and non-ideal interfaces in dirty ferromagnet/superconductor junctions (2007)
We study the proximity-induced superconducting correlations as well as the local density of states of a ferromagnet, in a ferromagnet/s-wave superconductor heterostructure. We include the effects of...