Print Email Facebook Twitter Electrodynamics of strongly disordered superconductors Title Electrodynamics of strongly disordered superconductors Author Coumou, P.C.J.J. Contributor Klapwijk, T.M. (promotor) Faculty Applied Sciences Department Kavli Institute of Nanoscience Delft Date 2015-02-06 Abstract Thin films of superconducting materials with a high resistance in the normal state, such as TiN, NbTiN, NbN and InO, are intensively studied from both an application and a fundamental point of view. A spatially inhomogeneous superconducting state can arise in these materials as a result of the strong disorder. This Thesis provides an experimental study of the evolution of the electromagnetic response with increasing disorder of superconducting thin films. We primarily investigate a series of disordered TiN films. The films are grown by means of plasma-enhanced atomic-layer deposition. We probe the electromagnetic response using superconducting microwave resonators. We find a gradual evolution of the electromagnetic response with disorder, deviating from the Mattis-Bardeen equations. This result might be attributed to changes in the quasiparticle density of states (DoS) induced by the disorder. We can describe the measured microwave response with a heuristic model which contains a disorder-dependent effective pair breaking parameter that modifies the DoS. Further, we compare the assumed DoS—used to describe the electrodynamics—to local tunnel spectra obtained using scanning tunneling spectroscopy. We find affirmative results for the lowest disordered film. However, we find a strong discrepancy for the most disordered film. Moreover, this film displays large variations in the local tunnel spectra. This result signals the breakdown of a model that is based on average properties, due to the emergence of a spatial inhomogeneous superconducting state. Subject superconductivitydisorderelectrodynamicsresonatorsTiNtitanium nitrideALDatomic layer deposition To reference this document use: https://doi.org/10.4233/uuid:ad01901d-511f-4496-ae66-301d0db92caa ISBN 978-90-8593-209-3 Part of collection Institutional Repository Document type doctoral thesis Rights (c) 2015 Coumou, P.C.J.J. Files PDF Thesis-PCJJ_Coumou.pdf 10.07 MB Close viewer /islandora/object/uuid:ad01901d-511f-4496-ae66-301d0db92caa/datastream/OBJ/view