NUM division - Publication Highlights

Frustrated magnets with spiral magnetic orders are of high current interest due to their potential for spintronics and low-power magnetoelectric devices. However, their low magnetic order temperatures (typically <100K) greatly restrict their fields of application. Researchers of PSI have demonstrated that the stability domain of the spiral phase in the perovskite YBaCuFeO₅ can be enlarged by more than 150K through a controlled manipulation of the Fe/Cu chemical disorder.

Sr₂CuTeO₆ presents an opportunity for exploring low-dimensional magnetism on a square lattice of S=1/2  Cu²⁺ ions. We employ ab initio multireference configuration interaction calculations to unravel the Cu²⁺ electronic structure and to evaluate exchange interactions in Sr₂CuTeO₆.

The influence of different background gases and substrate heating on the plasma plume dynamics from silver ablation is investigated by species selected time and space resolved imaging. The results provide a time-resolved understanding on how those process parameters affect the expansion: from a free expansion in vacuum with velocities exceeding 20'000 m/s to a very slow expansion in Ar at 1 × 10⁻¹ mbar with arrival velocities of 280 m/s.

Lattice vibrations (phonons) in crystals are typically weakly interacting with the electronic and magnetic degrees of freedom, such as charge and spin fluctuations. Researchers of PSI together with collaborators from EPF Lausanne, Japan and USA discovered an unexpectedly strong coupling between lattice vibrations and spin fluctuations in the quantum magnet LiCrO₂. The observed magnetoelastic waves or electromagnons carry both electric and magnetic dipole moment.

Here we present a study of magnetism in Co_0.05Ti_0.95O_2−δ anatase films grown by pulsed laser deposition under a variety of oxygen partial pressures and deposition rates. Energy-dispersive spectrometry and transmission electron microscopy analyses indicate that a high deposition rate leads to a homogeneous microstructure, while a very low rate or postannealing results in cobalt clustering.

By means of magnetization, specific heat, and muon-spin relaxation measurements, we investigate newly synthesized high-pressure oxidized Cu_0.75Mo_0.25Sr₂YCu₂O_7.54, in which overdoping is achieved up to p ˜ 0.46 hole/Cu, well beyond the T_c-p superconducting dome of cuprates, where Fermi-liquid behavior is expected.

The deuteron — one of the simplest atomic nuclei, consisting of just one proton and one neutron — is considerably smaller than previously thought. This finding was arrived at by an international research group that carried out experiments at the Paul Scherrer Institute, PSI. The new result is consistent with a 2010 study by the same group, in which the researchers measured the proton and found a significantly smaller value than previous research using different experimental methods.

Epitaxial thin films of the proton-conducting perovskite BaZr_0.53In_0.47O_3−δH_0.47−2δ, grown by pulsed laser deposition, were investigated in their hydrated and dehydrated conditions through a multitechnique approach with the aim to study the structure and proton concentration depth profile and their relationship to proton conductivity.

Pressure-induced ordering close to a z = 1 quantum-critical point is studied in the presence of bond disorder in the quantum spin system (C₄H₁₂N₂)Cu₂(Cl_1−xBr_x)₆ (PHCX) by means of muon-spin rotation and relaxation.