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The oxygen deficiencyδin YBa2Cu3O7−δ(YBCO) plays a crucial role for affecting high-temperature superconductivity. We applied (coincident) Doppler broadening spectroscopy of theelectron-positron annihilation line to study in situ the temperature dependence of the oxygen con-centration and its depth profile in single crystalline YBCO film grown on SrTiO3(STO) substrates.The oxygen diffusion during tempering was found to lead to a distinct depth dependence ofδ, whichis not accessible using X-ray diffraction. [...]

In the cubic rare-earth pyrochlore Ho2Ti2 O7 , the magnetic holmium ions sit on a tetraedricrare-earth sublattice and experience strong crystalline electric field effects. The resultingpronounced local h111i-Ising anisotropy, in the combination with ferromagnetic coupling,creates a macroscopically degenerate ground state. [...]

While spherical particles are the most studied viscosity modifiers, they are well known only to increase viscosities, in particular at low concentrations. Extended studies and theories on non-spherical particles find a more complicated behavior, but still a steady increase. [...]

Spin waves in chiral magnetic materials are strongly influenced by the Dzyaloshinskii-Moriya interaction (DMI) resulting in various intriguing phenomena like non-reciprocal magnon propagation and magnetochiral dichroism. The DMI also stabilizes spatially periodic magnetic textures, in particular, helimagnetic order and skyrmion lattices that naturally give rise to magnon band structures with interesting prospects for magnonics applications. [...]

Temperature-driven polyamorphism has been reported in various supercooled liquids and glasses. The dynamical and structural routes followed by the system during such crossovers are however not universal and appear to be related to intrinsic kinetic properties of the liquid. [...]

In this Letter, we demonstrate that a small but finite ferroelectric polarization in orthorhombic LuFeO$_3$ is primarily of electronic origin (oriented along a-axis) driven by commensurate (k = 0) and collinear magnetic structure. The nonpolar orthorhombic lattice (space group $Pnma$) undergoes isostructural transition at the magnetic transition temperature $T_N$ ($\sim$600 K). [...]

We present high-resolution thermal-expansion and specific-heat measurements of single crystalline alpha-RuCl3. An extremely hysteretic structural transition expanding over 100 K is observed by thermal- expansion along both crystallographic axes, which we attribute to a change of stacking sequence of the RuCl3 layers. [...]

We report the direct observation of the in-situ temperature-dependent surface segregation of Ni adatoms on single crystalline Pd surfaces using Positron annihilation induced Auger Electron Spectroscopy (PAES). For this study, a single atomic layer of Ni was grown on Pd with the crystallographic orientations Pd(111), Pd(110) and Pd(100). [...]

The quantification of the dose rate and the composition of the dose in the vicinity of supermirror coated guides is essential for designing shielding for beamlines transporting neutrons with a high flux. We present results on a calculation of radiative neutron absorption in Ni/Ti and NiMo/Ti supermirror coatings which leads to the emission of high energy gamma rays. [...]