Related papers: Preparation and STM study of clean Nb(111) surface…
We perform electric double-layer gating experiments on thin films of niobium nitride. Thanks to a cross-linked polymer electrolyte system of improved efficiency, we induce surface charge densities as high as $\approx 2.8 \times…
In the present work the chemical composition of niobium surface upon 200-400 {\deg}C baking similar to "medium-temperature baking" and "furnace baking" of cavities is explored in-situ by synchrotron X-ray photoelectron spectroscopy (XPS).…
We characterize low-loss electron-beam evaporated niobium thin films deposited under ultra-high vacuum conditions. Slow deposition yields films with a high superconducting transition temperature ($9.20 \pm 0.06 \rm ~K$) as well as a…
A new surface treatment technique for niobium (Nb) Superconducting Radio Frequency (SRF) cavities called Buffered Electropolishing (BEP) has been developed at JLab. It was found that BEP could produce the smoothest surface finish on Nb…
Four-point measurements using a multi-tip scanning tunneling microscope (STM) are carried out in order to determine surface and step conductivities on Si(111) surfaces. In a first step, distance-dependent four-point measurements in the…
Scanning tunneling luminescence microscopy (STLM) along with scanning tunneling spectroscopy (STS) is applied to a step-bunched, oxidized 4H-SiC surface prepared on the silicon face of a commercial, n-type SiC wafer using a silicon melt…
Lithium doped sodium niobate is an ecofriendly piezoelectric material that exhibits a variety of structural phase transitions with composition and temperature. We have investigated the phase stabilities of an important composition…
Among the recognized sources of decoherence in superconducting qubits, the spatial inhomogeneity of the superconducting state and the possible presence of magnetic-flux vortices remain comparatively underexplored. Niobium is commonly used…
Leveraging scanning tunneling microscopy (STM) for atomic-scale fabrication has led to many advancements such as the creation of atomic electron-spin qubit structures on surfaces. However, the time-consuming and tedious nature of this…
Originally developed technique based on generation of plasma-cluster flux emitted from cathode spots at surface of an integrally cold cathode has been applied for deposition of niobium superconductive (thick) film materials. Possibility for…
Chemically inert Coatings on Havar entrance foils of the targets for [18F] production via proton irradiation of enriched water at pressurized conditions are needed to decrease the amount of ionic contaminants released from Havar. In order…
Cold electropolishing (EP) of a nitrogen-doped (N-doped) niobium (Nb) superconducting RF (SRF) cavity was found to improve its quality factor. In order to understand the effect of EP temperature on N-doped and undoped surfaces, a systematic…
Surface preparation of niobium superconducting RF cavities is a critical step for achieving good RF performance under the superconducting state. Surface defect, roughness, and contamination affect the accelerating gradient and quality…
The results of determination of critical magnetic fields, magnetization curves and critical currents of niobium samples of different purity are presented. It is shown that ultrapure niobium near Tc is a superconductor of the first type and…
Atomic layer deposition was used to synthesize niobium silicide (NbSi) films with a 1:1 stoichiometry, using NbF5 and Si2H6 as precursors. The growth mechanism at 200oC was examined by in-situ quartz crystal microbalance (QCM) and…
We present a novel transmon qubit fabrication technique that yields systematic improvements in T$_1$ relaxation times. We fabricate devices using an encapsulation strategy that involves passivating the surface of niobium and thereby…
Vacuum thermal treatments (baking) are known to improve the superconducting properties of the RF surface layer of niobium cavities, and are employed as a last processing step to increase their efficiency determined by intrinsic quality…
Correlating structure with electronic functionality is central to the engineering of quantum materials and devices whose properties depend sensitively on disorder. Transmission electron microscopy (TEM) offers high spatial resolution…
We report the construction and performance of a low temperature, high field scanning tunneling microscope (STM) operating down to 350mK and in magnetic fields up to 9T, with thin film deposition and in-situ cleaving capabilities. The main…
Bismuth Selenide (Bi$_{2}$Se$_{3}$) is a topological insulator (TI) with a structure consisting of stacked quintuple layers. Single crystal surfaces are commonly prepared by mechanical cleaving. This work explores the use of low energy…