Search results for "Solid"

Solid State Analogue of a Double Slit Interferometer

2002

In a conventional optical double slit interferometer Fig. 1a light emerges from a source at a point O’, passes through two slits A and B and forms an interference pattern at a point O. If the source provides monochromatic radiation the coherence between optical paths O’AO and O’BO is preserved at all reasonable scales. The intensity of the interference pattern at a given point O can be altered by changing the distance ∣O’AO∣ - ∣O’BO∣.

Excitation of rotons in parahydrogen crystals: The laser-induced-molecular-alignment mechanism

2013

Solid parahydrogen (p-H₂) is known to support long-lived coherences, of the order of 100 ps, which enables high-resolution spectroscopy in the time domain. Rotational Raman-type excitations to sublevels of J=2 are delocalized due to electric-quadrupole–quadrupole coupling in p-H₂ crystals, and the resulting states can be characterized as rotons. Wave packets of rotons exhibit molecular alignment with respect to laboratory coordinates. Here the concept of field-free molecular alignment, induced by strong ultrashort laser pulses, is extended into a molecular solid case. We derive a solid-state analog for the gas-phase alignment measure and illustrate the time-dependent alignment degree in p-H…

Passive optical resonator for OSQAR LSW experiment

2016

This paper treats the issue of locking a solid state laser, pumped by high power diodes (Verdi V5), to a twenty meter long optical resonator for OSQAR LSW - light shining through the wall, dark matter search experiment. In this paper the optical design and a possible locking scheme are presented. The environmental conditions in SM18 testing hall at CERN, where OSQAR experiment is based, are discussed. The main focus is put on the vibration analysis, cavity transversal modes behaviour, possible clipping in the anticryostat of LHC – Large Hadron Collider magnet bore and locking loop parameters required for future experimental testing. The expected finesse of resonator will be presented and di…

Temperature-Dependent Change of the Electronic Structure in the Kondo Lattice System $YbRh_{2}Si_{2}$

2021

Seminar, Deutschland; Journal of physics / Condensed matter 00(00), 1-20 (2021). doi:10.1088/1361-648X/abe479

The Statistical Description of de Haas—van Alphen Oscillations in Silicon Nanosandwich

2020

Here, we present room temperature de Haas—van Alphen oscillations measured in silicon nanosandwich in a weak magnetic field. Our results demonstrate a decrease of the oscillation magnitude with increasing magnetic field strength. This behavior is drastically different from the results reported earlier and it is attributed to the low-dimensionality of the studied structure, which enables room temperature observation of the de Haas—van Alphen effect in moderate magnetic fields up to 1000 Oe. We employ the classic Lifshitz-Kosevich formalism based on the dependence of the carrier effective mass on the applied magnetic field, to statistically describe this effect. We note that the statistical a…

Laser-driven quantum magnonics and terahertz dynamics of the order parameter in antiferromagnets

2017

The impulsive generation of two-magnon modes in antiferromagnets by femtosecond optical pulses, so-called femto-nanomagnons, leads to coherent longitudinal oscillations of the antiferromagnetic order parameter that cannot be described by a thermodynamic Landau-Lifshitz approach. We argue that this dynamics is triggered as a result of a laser-induced modification of the exchange interaction. In order to describe the oscillations we have formulated a quantum mechanical description in terms of magnon pair operators and coherent states. Such an approach allowed us to} derive an effective macroscopic equation of motion for the temporal evolution of the antiferromagnetic order parameter. An impli…

Unsuspended mass of solid particles in stirred tanks

1998

On propose une technique originale pour la determination de la fraction de particules solides non suspendues a des vitesses d'agitation inferieures a N js . La technique repose sur le concept des systemes jumeles et est completee par une technique de tracage et de detection pour la phase solide. Les resultats obtenus avec un reservoir chicane agite par une turbine Rushton, montrent que la fraction de solides ne quittant jamais le fond du reservoir peut etre simplement correlee au rapport entre la vitesse d'agitation et la vitesse de suspension complete de Zwietering. On montre qu'a des vitesses de l'agitateur d'environ 80% de la vitesse de suspension complete de Zwietering, pratiquement tou…

Understanding the glass transition and the amorphous state of matter: can computer simulation solve the challenge?

1999

The glass transition of supercooled fluids is one of the big puzzles of condensed matter physics, because there occurs a dramatic slowing down (the viscosity η can increase from about η = 1 Poise at the melting transition to η 10 13 Poise at the glass transition temperature T g ), but one hardly sees any accompanying change in the static structure. Theoretical concepts are very controversial - e.g., the Gibbs-di Marzio theory attributes glassy freezing to an underlying entropy catastrophe (the entropy of the supercooled fluid would fall below the crystal entropy at the Kauzmann temperature T 0 T g . Computer simulations offer the advantage that atomistically detailed information on structur…

2017

Accretion dynamics in the formation of young stars is still a matter of debate because of limitations in observations and modeling. Through scaled laboratory experiments of collimated plasma accretion onto a solid in the presence of a magnetic field, we open a first window on this phenomenon by tracking, with spatial and temporal resolution, the dynamics of the system and simultaneously measuring multiband emissions. We observe in these experiments that matter, upon impact, is ejected laterally from the solid surface and then refocused by the magnetic field toward the incoming stream. This ejected matter forms a plasma shell that envelops the shocked core, reducing escaped x-ray emission. T…

A Fractional Approach to Non-Newtonian Blood Rheology in Capillary Vessels

2019

In small arterial vessels, fluid mechanics involving linear viscous fluid does not reproduce experimental results that correspond to non-parabolic profiles of velocity across the vessel diameter. In this paper, an alternative approach is pursued introducing long-range interactions that describe the interactions of non-adjacent fluid volume elements due to the presence of red blood cells and other dispersed cells in plasma. These non-local forces are defined as linearly dependent on the product of the volumes of the considered elements and on their relative velocity. Moreover, as the distance between two volume elements increases, the non-local forces decay with a material distance-decaying …