Related papers: Evidence for quantized vortex entry in Nb3Sn under…
Nb$_3$Sn is currently the most promising material other than niobium for future superconducting radiofrequency cavities. Critical fields above 120 mT in pulsed operation and about 80 mT in CW have been achieved in cavity tests. This is…
We study mechanisms of vortex nucleation in Nb$_3$Sn Superconducting RF (SRF) cavities using a combination of experimental, theoretical, and computational methods. Scanning transmission electron microscopy (STEM) image and energy dispersive…
The high frequency vortex motion in Nb$_3$Sn was analyzed in this work up to 12 T. We used a dielectric loaded resonator tuned at 15 GHz to evaluate the surface impedance $Z$ of a Nb$_3$Sn bulk sample (24.8 at.\%Sn). From the field induced…
We use a near-field magnetic microwave microscope to investigate and compare rf vortex nucleation in two superconducting radio-frequency (SRF)-quality Nb3Sn films fabricated by different methods: a conventional vapor-diffused film and an…
The conditions for the entry of vortices into type-II superconductors being in the Meissner and/or mixed state, are studied by both numerical and analytical solution of the Ginzburg-Landau equations. A modulation instability of the…
While Nb3Sn theoretically offers better superconducting RF cavity performance (Q0 and Eacc) to Nb at any given temperature, peak RF magnetic fields consistently fall short of the 400 mT prediction. The relatively rough topography of…
The performance of superconducting radio-frequency (SRF) cavities is sometimes limited by local defects. To investigate the RF properties of these local defects, especially those that nucleate RF magnetic vortices, a near-field magnetic…
In this work, microwave measurements carried out in dielectric-loaded resonators exposed to high magnetic fields are exploited to yield the surface impedance of Nb$_3$Sn superconducting coatings deposited via two different techniques: vapor…
Theoretical limits to the performance of superconductors in high magnetic fields parallel to their surfaces are of key relevance to current and future accelerating cavities, especially those made of new higher-Tc materials such as Nb$_3$Sn,…
Nb Superconducting Radio-Frequency (SRF) cavities are observed to break down and lose their high-Q superconducting properties at accelerating gradients below the limits imposed by theory. The microscopic origins of SRF cavity breakdown are…
Nb3Sn (Tc ~ 18 K and Hsh ~ 400 mT) is a prospective material to replace Nb (Tc ~ 9 K and Hsh ~ 200 mT) in SRF accelerator cavities for significant cost reduction and performance enhancement. Because of its material properties, Nb3Sn is best…
We demonstrate the detection and control of individual Abrikosov vortices in superconducting microwave resonators. $\lambda/4$ resonators with a narrowed region near the grounded end acting as a vortex trap were fabricated and studied using…
Quantized vortices in type-II superconductors provide insights into the mechanisms of superconductivity. However, the generation of antivortices, characterized by magnetization antiparallel to the external magnetic field, remains less…
The melting of the magnetic vortex lattice has been observed in high-Tc superconductors in many experiments by different groups and is regarded as confirmed. To date, only one group claims to have observed the vortex-lattice melting in the…
Nanowires of two-dimensional (2D) crystals of type-II superconductor NbSe$_2$ prepared by electron-beam lithography were studied, focusing on the effect of the motion of Abrikosov vortices. We present magnetoresistance measurements on these…
For a type-II superconductor, when the applied magnetic field is higher than the lower critical value Hc1, the magnetic flux will penetrate into the superconductor and form quantized vortices, which usually are arranged in an Abrikosov…
To investigate the dynamics of driven vortices in superconductors, noise in the local vortex density was investigated in the mixed state of a high-$T_c$ superconductor, Bi$_2$Sr$_2$CaCu$_2$O$_y$, using a two-dimensional electron gas (2DEG)…
The response of vortex state to the magnetic field in Nb3Sn is probed using muon spin rotation and small-angle neutron scattering. A transformation of vortex structure between hexagonal and squared lattice is observed over a relatively low…
Equilibrium vortex configuration in conventional type II superconductors containing columnar defects is theoretically investigated. Near the upper critical field a single defect causes a strong local deformation of the vortex lattice. This…
Analytical formula to evaluate the vortex-penetration field at a groove with a depth smaller than penetration depth is derived, which can be applied to surfaces of cavities or test pieces made from extreme type II superconductors such as…