Here you find current and previous news from the PSI Center for Neutron and Muon Sciences.
Magnetoelastic Excitations in the Pyrochlore Spin Liquid Tb2Ti2O7
Tb2Ti2O7 is often referred to as a spin liquid as it does indeed remain in a magnetically disordered phase with spin dynamics down to 0.05 K, but this itself is a surprise since there are strong expectations of magnetic order and/or a structural distortion. However, throughout the spin liquid regime there are also strong signs of magnetoelastic coupling, leading to the suggestion that both spin and structural degrees of freedom are frustrated.
Bulk superconductivity in undoped T'-La1.9Y0.1CuO4 probed by muon spin rotation
The Meissner effect has been directly demonstrated by depth-resolved muon spin rotation measurements in high-quality thin films of the T'-structured cup rate, T'-La1.9Y0.1CuO4, to confirm bulk superconductivity (Tc ≈ 21 K) in its undoped state. The gradual expelling of an external magnetic field is observed over a depth range of ∼ 100 nm in films with a thickness of 275(15) nm, from which the penetration depth is deduced to be 466(22) nm. Based on this result, we argue that the true ground state of the “parent” compound of the n-type cuprates is not a Mott insulator but a strongly correlated metal with colossal sensitivity to apical oxygen impurities.