The performance of superconducting radiofrequency (SRF) cavities used for particle accelerators depends on two characteristic material parameters: field of first flux entry Hentry and pinning strength. The former sets the limit for the maximum achievable accelerating gradient, while the latter determines how efficiently flux can be expelled related to the maximum achievable quality factor. In this paper, a method based on muon spin rotation (µSR) is developed to probe these parameters on samples. It combines measurements from two different spectrometers, one being specifically built for these studies and samples of different geometries. It is found that annealing at 1400 • C virtually eliminates all pinning. Such an annealed substrate is ideally suited to measure Hentry of layered superconductors, which might enable accelerating gradients beyond bulk niobium technology.Recently, to reach high quality factors, a treatment procedure has been established baking cavities at 800 • C and injecting nitrogen gas at the end of this treatment. arXiv:1705.05480v3 [cond-mat.supr-con]

We report on a strong perpendicular magnetic anisotropy in [CoFe 0.4nm/Pd t] 6 (t = 1.0-2.0 nm) multilayers fabricated by DC sputtering in a ultrahigh vacuum chamber. Saturation magnetization, M s , and uniaxial anisotropy, K u , of the multilayers decrease with increasing the spacing thickness, with a M s of 155 emu/cc and a K u of 1.14×10 5 J/m 3 at a spacing thickness of t = 2 nm. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements reveal that spin and orbital magnetic moments of Co and Fe in CoFe film decrease as function of Pd thickness, indicating the major contribution of surface/interfacial magnetism to the magnetic properties of the film.

Temperature-dependent and anisotropic optical response of layered Pr0.5Ca1.5MnO4 probed by spectroscopic ellipsometry Majidi, M. A.; Thoeng, E.; Gogoi, P. K.; Wendt, F.; Wang, S. H.; Santoso, I.; Asmara, T. C.; Handayani, I. P.; van Loosdrecht, P. H. M.; Nugroho, A. A.

A new high field spectrometer has been built to extend the capabilities of the β-detected nuclear magnetic resonance ( β-NMR) facility at TRIUMF. This new beamline extension allows β-NMR spectroscopy to be performed with fields up to 200 mT parallel to a sample’s surface (perpendicular to the ion beam), allowing depth-resolved studies of local electromagnetic fields with spin polarized probes at a much higher applied magnetic field than previously available in this configuration. The primary motivation and application is to allow studies of superconducting radio frequency (SRF) materials close to the critical fields of Nb metal, which is extensively used to fabricate SRF cavities. The details of the design considerations and implementation of the ultra-high vacuum (UHV) system, ion optics, and beam diagnostics are presented here. Commissioning of the beamline and spectrometer with radioactive ions are also reported here. Future capabilities and applications in other areas are also described.