Isotopieeffekte in Ladungsübertragungsreaktionen

Für Ladungsübertragungsreaktionen im. Bereich niedriger kinetischer Energien zwischen Edelgasionen (He⁺, Ar⁺) und zweiatomigen Molekülen (¹⁴N₂, ¹⁵N₂) werden Wirkungsquerschnitte und Isotopieeffekte im Rahmen der statistischen phasenraumtheorie berechnet. Bei niedrlgen kinetischen Energien zeigt das statistische Modell wesentliche Isotopieeffekte und inverse Isotopieeffekte in speziellen Reaktionskanälen.     

Ladungstransport in dünnen Filmen

The electronic charge transport in thin indium films of high purity is investigated (direct current, eddy current and magnetoresistance in a magnetic field perpendicular to the surface) at low temperatures where surface scattering of the electrons becomes important. A method is described which allows the determination of the mean free path (corresponding to a Sommerfeld-model for the conduction electrons) for a single specimen by measuring both the direct current conductivity and the decay time of eddy currents. For a multivalent metal like indium, with a Fermi surface extending over different Brillouin zones, the “mean free path” evaluated in this way can no longer be regarded as the mean value of the electronic free path calculated over the whole Fermi surface. It is shown, that for indium the ?mean free path” evaluated from our size effect investigations will mainly correspond to the electrons of the second zone, and that the electrons of the third zone only neglectingly contribute to the electronic charge transport.     

Gebundene Paare in Fermi-Flüssigkeiten

The effect of a hard core on the energy of bound pair states in fermi-liquids is considered. It turns out that such bound pairs can exist in nuclear matter for the real nuclear forces, but not in the (non superfluid) He³. The importance of this fact for a possible understanding of the superfluidity is discussed briefly.     

Zur Kernfusion in Myonmolekülen

Using results of a preceding paper, the wavefunctions of nuclear vibrations in muon molecules have been calculated by numerical integration, especially at small nuclear distances. These functions have then been used to determine reaction rates of nuclear fusion. The effect of nuclear forces on the wavefunction at very small distances has been estimated and taken account of. The numerical results reasonably agree with (pμd) experiments.     

Spin transition in magnesiowüstite in earth's lower mantle

Iron in the major lower mantle (LM) minerals undergoes a high spin (HS) to low spin (LS) transition at relevant pressures (23-135 GPa). Previous failures of standard first principles approaches to describe this phenomenon have hindered its investigation and the clarification of important consequences. Using a rotationally invariant formulation of LDA + U we report a successful study of this transition in low solute concentration magnesiowüstite, (Mg(1-x)Fe(x)(O), (x < 0.2) the second most abundant LM phase. We show that the HS-LS transition goes through an insulating (semiconducting) intermediate mixed spins (MS) state without discontinuous changes in properties, as seen experimentally. We show that the HS state crosses over smoothly to the LS state passing through an insulating MS state where properties change continuously, as seen experimentally.     

Maxwell-Jüttner distributions in relativistic molecular dynamics

In relativistic kinetic theory, which underlies relativistic hydrodynamics, the molecular chaos hypothesis stands at the basis of the equilibrium Maxwell-J ttner probability distribution for the four-momentum p^α. We investigate the possibility of validating this hypothesis by means of microscopic relativistic dynamics. We do this by introducing a model of relativistic colliding particles, and studying its dynamics. We verify the validity of the molecular chaos hypothesis, and of the Maxwell-J ttner distributions for our model. Two linear relations between temperature and average kinetic energy are obtained in classical and ultrarelativistic regimes.     

Migdal and his theory in Jülich

We review the application of Migdal’s Theory of Finite Fermi Systems to the structure of deformed nuclei, approaches beyond the conventional linear response, and microscopic calculations of the Migdal-parameters.     

Wellenstruktur der Magnetisierung in dünnen Permalloyschichten

The magnetic ripple of thin uniaxial permalloy films is estimated by the calculus of variations. Two special cases are examined, namely average magnetization and external field in the easy and in the hard direction of the uniaxial anisotropy. When the fluctuations of the magnetization, which are connected with the fluctuations of the anisotropy, are small, the variation problem leads to differential equations which can be integrated. The solutions describe the magnetic ripple in the film. The ripple is a function of the dispersion of the anisotropy directions, the magnetic constants of the film, its thickness, and of the applied field. The agreement between theory and experiment is good.     

Bestimmung schwacher Absorptionen in dünnen dielektrischen Schichten

By a method specially developped for high accuracy, the weak absorption of thin dielectric films was measured and coefficients of absorption were evaluated. Results are stated for such substances as cryolithe, MgF₂, NaF, paraffin, ZnS and Sb₂O₃, which are used for the production of dielectric reflecting films.     

Phase-sensitive Landau-Zener-Stückelberg interference in superconducting quantum circuit

Superconducting circuit quantum electrodynamics(QED)architecture composed of superconducting qubit and resonator is a powerful platform for exploring quantum physics and quantum information processing.By employing techniques developed for superconducting quantum computing,we experimentally investigate phase-sensitive Landau-Zener-Stückelberg(LZS)interference phenomena in a circuit QED.Our experiments cover an extensive range of LZS transition parameters and demonstrate the LZS induced Rabi-like oscillation as well as phase-dependent steady-state population.