SμS: Swiss Muon Source

Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd₂As₂. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations.

Nb₃Sn 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 large compared to the lower critical field as derived from the London penetration depth, extracted from low field surface impedance measurements. 

A method to measure the superconducting (SC) stiffness tensor ρ_s, without subjecting the sample to external magnetic field, is applied to La_1.875Sr_0.125CuO₄. The method is based on the London equation J=-ρ_sA, where J is the current density and A is the vector potential which is applied in the SC state.