Paul Scherrer Institute

About: Paul Scherrer Institute is a facility organization based out in Villigen, Switzerland. It is known for research contribution in the topics: Neutron & Large Hadron Collider. The organization has 9248 authors who have published 23984 publications receiving 890129 citations. The organization is also known as: PSI.

Spin-state transition in LaCoO3: direct neutron spectroscopic evidence of excited magnetic states.

Abstract: A gradual spin-state transition occurs in LaCoO3 around T ∼ 80 −120 K, whose detailed nature remains controversial. We studied this transition by means of inelastic neutron scattering (INS), and found that with increasing temperature an excitation at ∼ 0.6 meV appears, whose intensity increases with temperature, following the bulk magnetization. Within a model including crystal field interaction and spin-orbit coupling we interpret this excitation as originating from a transition between thermally excited states located about 120 K above the ground state. We further discuss the nature of the magnetic excited state in terms of intermediate-spin (IS, t 5g e 1 , S = 1) vs. highspin (HS, t 4g e 2, S = 2) states. Since the g-factor obtained from the field dependence of the INS is g ∼ 3, the second interpretation looks more plausible.

Study on the chemical character of water soluble organic compounds in fine atmospheric aerosol at the Jungfraujoch

Abstract: In this study the chemical nature of the bulk of water soluble organic compounds in fine atmospheric aerosol collected during summer 1998 at the Jungfraujoch, Switzerland (3580 m asl) is characterised. The mass concentration of water soluble organic substances was similar to those of major inorganic ions, and the water soluble organic matter was found to be composed of two main fractions: (i) highly polyconjugated, acidic compounds with a varying degree of hydrophobicity and (ii) slightly polyconjugated, neutral and very hydrophilic compounds. The contribution of both fractions to the total water soluble organic carbon was about 50%. Separation into individual components was impossible either by HPLC or capillary electrophoresis which indicates the presence of a high number of chemically similar but not identical species. Results obtained by ultrafiltration and HPLC-MS have shown that the molecular weights are of the order of several hundreds. Most of the protonation constants for the acidic compounds determined by capillary electrophoresis were in the range 104–107.

Magnetic excitations and phase separation in the underdoped La2-xSrxCuO4 superconductor measured by resonant inelastic X-ray scattering.

Abstract: We probe the collective magnetic modes of ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$ and underdoped ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ (LSCO) by momentum resolved resonant inelastic x-ray scattering (RIXS) at the Cu ${L}_{3}$ edge. For the undoped antiferromagnetic sample, we show that the single magnon dispersion measured with RIXS coincides with the one determined by inelastic neutron scattering, thus demonstrating that x rays are an alternative to neutrons in this field. In the spin dynamics of LSCO, we find a branch dispersing up to $\ensuremath{\sim}400\text{ }\text{ }\mathrm{meV}$ coexisting with one at lower energy. The high-energy branch has never been seen before. It indicates that underdoped LSCO is in a dynamic inhomogeneous spin state.

Exact chiral symmetry, topological charge and related topics

Abstract: It has been shown recently that Dirac operators satisfying the Ginsparg-Wilson relation provide a solution of the chirality problem in QCD at finite lattice spacing. We discuss different ways to construct these operators and their properties. The possibility to define lattice chiral gauge theories is briefly discussed as well.