Imaging of vortex configurations in thin films by scanning-tunneling microscopy

Abstract

We report on imaging of vortices in thin superconducting films using surface passivation with an ultrathin Au layer. This allows investigation of surfaces that oxidize easily, as well as the mounting of samples in air. We studied vortex configurations in a material with weak vortex pinning (a-Mo2.7Ge) and a strongly pinning material (NbN) at 4.2 K in magnetic fields up to 1.4 T. In a-Mo2.7Ge, we observe a well-ordered hexagonal lattice, with local defects beginning to appear around 1.0 T. In NbN, the vortex lattice is fully disordered.

Fluorescent Cyclic Voltammetry of Immobilized Azurin: Direct Observation of Thermodynamic and Kinetic Heterogeneity

“…Thin gold films were prepared either by RF sputtering (ATC 1800F, AJA International) or evaporation (Edward Auto 306 cryo evaporator). Sputtering was performed as described by van Baarle et al 45. Azurin was immobilized on the working electrode through a self‐assembling monolayer (SAM) of 1‐hexanethiol (wt azurin) or 1‐octanethiol (zinc azurin and N42C).…”

Fluorescent Cyclic Voltammetry of Immobilized Azurin: Direct Observation of Thermodynamic and Kinetic Heterogeneity

“…Thin gold films were prepared either by RF sputtering (ATC 1800F, AJA International) or evaporation (Edward Auto 306 cryo evaporator). Sputtering was performed as described by van Baarle et al [45] Azurin was immobilized on the working electrode through a self-assembling monolayer (SAM) of 1hexanethiol (wt azurin) or 1-octanethiol (zinc azurin and N42C). For more details see section 11 in the Supporting Information.…”

A Boost for Superconducting Logic

“…4, this is counteracted by the lower interface transparency. In this respect, it should also be remarked that the set TSV50 is surprisingly efficient when taking into account that the S-layer thickness is about 10 times the superconducting coherence length ξ S , which for MoGe is about 5 nm [24]. This again appears to be a consequence of the 100% spin-polarized ferromagnet.…”