Related papers: Depth-resolved Characterization of Meissner Screen…
We report observation of the nonlinear Meissner effect (NLME) in Nb films by measuring the resonance frequency of a planar superconducting cavity as a function of the magnitude and the orientation of a parallel magnetic field. Use of low…
We investigate "hot" regions with anomalous high field dissipation in bulk niobium superconducting radio frequency cavities for particle accelerators by using low energy muon spin rotation (LE-$\mu$SR) on corresponding cavity cutouts. We…
Non-invasive magnetic field sensing using optically - detected magnetic resonance of nitrogen-vacancy (NV) centers in diamond was used to study spatial distribution of the magnetic induction upon penetration and expulsion of weak magnetic…
Recent advances in surface treatments of Niobium superconducting radio frequency (SRF) cavities have led to substantially increased Q-factors and maximum surface field. This poses theoretical challenges to identify the mechanisms…
We report the finding of new surface treatments that permit to manipulate the niobium resonator nitrogen content in the first few nanometers in a controlled way, and the resonator fundamental Mattis-Bardeen surface resistance and residual…
A method for determining the internal DC magnetic field inside a superconducting cavity is presented. The method relies on the relationship between magnetic field and frequency of the Kittel mode of a ferrimagnetic sphere, hybridised in the…
Tunneling spectroscopy was performed on Nb pieces prepared by the same processes used to etch and clean superconducting radio frequency (SRF) cavities. Air exposed, electropolished Nb exhibited a surface superconducting gap delta=1.55 meV,…
This comprehensive study, being part of the European XFEL R\&D effort, elucidates the influence of medium temperature (mid-T) heat treatments between 250{\deg}C and 350{\deg}C on the performance of 1.3~GHz superconducting radiofrequency…
The decay of $^{19}$O($\beta^-$) and $^{19}$Ne($\beta^+$) implanted in niobium in its superconducting and metallic phase was measured using purified radioactive beams produced by the SPIRAL/GANIL facility. Half-lives and branching ratios…
A systematic study of irreversible magnetization was performed in bulk Niobium after different surface treatments. Starting with smooth surfaces and abrading them, a strong increase of the critical current is observed up an apparent…
The radio-frequency surface resistance of niobium resonators is incredibly reduced when nitrogen impurities are dissolved as interstitial in the material, conferring ultra-high Q-factors at medium values of accelerating field. This effect…
We report on the realization and characterization of a magnetic microtrap for ultra cold atoms near a straight superconducting Nb wire with circular cross section. The trapped atoms are used to probe the magnetic field outside the…
Pressure is a key parameter for tuning or revealing superconductivity in materials and compounds. Many measurements of superconducting phase transition temperatures have been conducted using diamond anvil cells (DACs), which provide a wide…
Paramagnetic Meissner Effect (PME) was observed in Co/Nb/Co trilayers and multilayers. Measurements of the response to perpendicular external field near the superconducting transition temperature were carried out for various Nb thicknesses.…
We report a method to locally measure the penetration depth $\lambda$ in a superconductor by detecting the diamagnetic response using magnetic force microscopy (MFM). We extract $\lambda$ by fitting the height dependence of the levitation…
We report magnetic force microscopy (MFM) measurements on the iron-based superconductor $\mathrm{Ba_{1-x}K_xFe_2As_2}$. By measuring locally the Meissner repulsion with the magnetic MFM tip, we determine the absolute value of the in-plane…
Microscopic studies on thin film superconductors play an important role for probing non-equilibrium phase transitions and revealing dynamics at the nanoscale. However, magnetic sensors with nanometer scale spatial and picosecond temporal…
The boundary effects in the screening of an applied magnetic field in a charged anyon fluid at finite temperature and density are investigated. By analytically solving the extremum equations of the sytem and minimizing the free energy…
Microwave spectroscopy is a powerful experimental tool to reveal information on the intrinsic properties of superconductors. Superconducting stripline resonators, where the material under study constitutes one of the ground planes, offer a…
Our objective is to study the extreme and local electrodynamic properties of Niobium (Nb), and to relate these properties to specific defects that limit the ultimate RF performance of superconducting radio frequency (SRF) cavities made from…