16 research outputs found
Proximity-Induced Odd-Frequency Superconductivity in a Topological Insulator
At an interface between a topological insulator (TI) and a conventional
superconductor (SC), superconductivity has been predicted to change
dramatically and exhibit novel correlations. In particular, the induced
superconductivity by an -wave SC in a TI can develop an order parameter with
a -wave component. Here we present experimental evidence for an unexpected
proximity-induced novel superconducting state in a thin layer of the
prototypical TI, BiSe, proximity coupled to Nb. From depth-resolved
magnetic field measurements below the superconducting transition temperature of
Nb, we observe a local enhancement of the magnetic field in BiSe that
exceeds the externally applied field, thus supporting the existence of an
intrinsic paramagnetic Meissner effect arising from an odd-frequency
superconducting state. Our experimental results are complemented by theoretical
calculations supporting the appearance of such a component at the interface
which extends into the TI. This state is topologically distinct from the
conventional Bardeen-Cooper-Schrieffer state it originates from. To the best of
our knowledge, these findings present a first observation of bulk odd-frequency
superconductivity in a TI. We thus reaffirm the potential of the TI-SC
interface as a versatile platform to produce novel superconducting states.Comment: Accepted version for publication in Physical Review Letter
Atomistic models and time-dependent simulations of spin dynamics in isolated and current-carrying systems
THESIS 10028Understanding and ultimately controlling the dynamics of electrons and their spins is an important aspect of spin-based electronics. Recent experimental advances open up new possibilities for probing spin dynamics with very high spatial and temporal resolution, i.e. in atomic-sized systems and at sub-picosecond time scales. At these lengths and times quantum effects and atomistic details can not be neglected and the applicability of classical models is limited. Therefore, there is a need to develop new methodologies and computational tools for atomistic modeling of spin dynamics, in particular in the presence of electric currents. In this Thesis we construct a computational scheme, capable of describing the time evolution of spin systems both in isolation and under current-carrying conditions. The method has been developed in the spirit of the tightbinding model but it is transferable to more accurate first-principles methods such as density functional theory. This computational tool is then used to investigate timedependent phenomena in the systems of interest