The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform

V.a. Atsarkin - One of the best experts on this subject based on the ideXlab platform.

  • Anomalous slowing down of the longitudinal spin relaxation near the antiferromagnetic phase transition in LaMnO_3 manganite
    Journal of Experimental and Theoretical Physics Letters, 2004
    Co-Authors: V.a. Atsarkin, V. V. Demidov, A. M. Balbashov
    Abstract:

    It has been found that, instead of the expected Critical Acceleration of the longitudinal spin relaxation near the Néel temperature in stoichiometric LaMnO_3 samples, the relaxation is sharply retarded. This slowing down is similar to that observed earlier in doped manganites with ferromagnetic ordering.

  • Electron spin relaxation in CMR manganites: absence of Critical Acceleration
    Journal of Magnetism and Magnetic Materials, 2003
    Co-Authors: V.a. Atsarkin, V. V. Demidov, Ferenc Simon, Richard Gaal, Yutaka Moritomo, K. Conder, András Jánossy, László Forró
    Abstract:

    Abstract Using original modulation technique, the longitudinal electron spin-lattice relaxation time T 1 has been measured in a series of nearly cubic La 1− x Ca x MnO 3 ( x =0.1; 0.2; 0.25; 0.33) and layered La 2−2 x Sr 1+2 x Mn 2 O 7 ( x =0.4 and 0.5) manganites both in paramagnetic state and around the temperature ( T c ) of the magnetic ordering. The data are compared with the evolution of the transverse relaxation time T 2 as determined from the ESR linewidth. Well above T c , the T 1 = T 2 equality is confirmed, whereas a pronounced slowing down of T 1 is observed in all the materials as T c is approached. The temperature dependence of T 1 is found to be consistent with that of Tχ ( T ), where χ ( T ) represents the temperature dependence of the electron-spin susceptibility determined from the ESR absorption area. The interpretation suggests freezing the local field fluctuations due to polarization of superparamagnetic clusters in the external magnetic field.

S. K. Sarma - One of the best experts on this subject based on the ideXlab platform.

  • Static and Seismic Slope Safety Displacement-Based Criterion for Seismic Analysis
    Developments in Geotechnical Engineering, 2018
    Co-Authors: S. K. Sarma
    Abstract:

    Methods of slope stability analyses for static and seismic conditions are discussed. The ideas of factor of safety, Critical Acceleration and Critical slip surface are examined. The idea of displacement of slopes during earthquakes is also discussed; it is emphasised that displacements are a better criterion for seismic design of slopes. Post-seismic large displacement of slopes is examined in a test case.

  • Determination of Critical slip surface in slope analysis
    Géotechnique, 2006
    Co-Authors: S. K. Sarma, D. Tan
    Abstract:

    A new method of finding the Critical slip surface in slope stability analysis is developed in this paper, based on the limit equilibrium technique with added stress acceptability criterion. The stress acceptability criterion is based on the limited strength of soil. The slip surface is developed in terms of the Critical Acceleration. The procedure uses stress acceptability as a prerequisite to derive a system of non-linear equations to determine the slip surface slice by slice upwards; no prior assumption of the shape of the surface is needed. This surface simultaneously satisfies the kinematical acceptability criterion. The whole procedure includes both homogeneous and non-homogeneous slopes. In terms of the minimum factor of safety, the obtained Critical slip surfaces compare well with those obtained through methods based on optimisation techniques. In addition, the solution provides information on the Critical Acceleration and the kinematically acceptable interslice boundaries for the analysis of seism...

  • Critical slip surface in slope stability analysis
    2004
    Co-Authors: Richard J. Jardine, David M. Potts, K G Higgins, S. K. Sarma
    Abstract:

    The key problem when performing slope stability analysis using the limit equilibrium technique is finding the Critical slip surface that produces the minimum factor of safety or the minimum Critical Acceleration. The acceptability of the solution is another problem with this approach. A new analysis technique, developed within the bounds of the limit equilibrium technique, utilises the acceptability criterion as the starting point. There is no a-priori assumption about the shape of the slip surface. The procedure develops the Critical acceptable surface for a given Critical Acceleration. The minimum Critical Acceleration along with the corresponding Critical surface is derived through iteration. For slopes of homogeneous material, the procedure is simple. It is interesting to see from the solution that Critical surface is close to a circle for homogeneous slopes rather than the log-spiral. It is planned to treat more complex non-homogeneous slopes in a subsequent paper. For the covering abstract see ITRD E128041.

László Forró - One of the best experts on this subject based on the ideXlab platform.

  • Electron spin relaxation in CMR manganites: absence of Critical Acceleration
    Journal of Magnetism and Magnetic Materials, 2003
    Co-Authors: V.a. Atsarkin, V. V. Demidov, Ferenc Simon, Richard Gaal, Yutaka Moritomo, K. Conder, András Jánossy, László Forró
    Abstract:

    Abstract Using original modulation technique, the longitudinal electron spin-lattice relaxation time T 1 has been measured in a series of nearly cubic La 1− x Ca x MnO 3 ( x =0.1; 0.2; 0.25; 0.33) and layered La 2−2 x Sr 1+2 x Mn 2 O 7 ( x =0.4 and 0.5) manganites both in paramagnetic state and around the temperature ( T c ) of the magnetic ordering. The data are compared with the evolution of the transverse relaxation time T 2 as determined from the ESR linewidth. Well above T c , the T 1 = T 2 equality is confirmed, whereas a pronounced slowing down of T 1 is observed in all the materials as T c is approached. The temperature dependence of T 1 is found to be consistent with that of Tχ ( T ), where χ ( T ) represents the temperature dependence of the electron-spin susceptibility determined from the ESR absorption area. The interpretation suggests freezing the local field fluctuations due to polarization of superparamagnetic clusters in the external magnetic field.

V. V. Demidov - One of the best experts on this subject based on the ideXlab platform.

Johann Rafelski - One of the best experts on this subject based on the ideXlab platform.

  • Critical Acceleration and Quantum Vacuum
    Modern Physics Letters A, 2013
    Co-Authors: Johann Rafelski, Lance Labun
    Abstract:

    Little is known about the physics frontier of strong Acceleration; both classical and quantum physics need further development in order to be able to address this newly accessible area of physics. In this lecture we discuss what strong Acceleration means, possible experiments using electron-laser collisions, and data available from ultra-relativistic heavy ion collisions. We review the foundations of the current understanding of charged particle dynamics in presence of Critical forces and discuss the radiation reaction inconsistency in electromagnetic theory and the apparent relation with quantum physics and strong field particle production phenomena. The role of the quantum vacuum as an inertial reference frame is emphasized, as well as the absence of such a 'Machian' reference frame in the conventional classical limit of quantum field theory.

  • Strong Field Physics: Probing Critical Acceleration and Inertia with Laser Pulses and Quark-Gluon Plasma
    arXiv: High Energy Physics - Phenomenology, 2010
    Co-Authors: Lance Labun, Johann Rafelski
    Abstract:

    Understanding physics in domains of Critical (quantum unstable) fields requires investigating the classical and quantum particle dynamics at the Critical Acceleration, $\dot u \to 1$ [natural units]. This regime of physics remains today experimentally practically untested. Particle and light collision experiments reaching Critical Acceleration are becoming feasible, in particular applying available high intensity laser technology. Ultra-relativistic heavy ion collisions breach the Critical domain but are complicated by the presence of much other physics. The infamous problem of radiation reaction and the challenging environment of quantum vacuum instability arising in the high field domain signal the need for a thorough redress of the present theoretical framework.

  • Strong Field Physics: Probing Critical Acceleration and Inertia with Laser Pulses and Quark-Gluon Plasma
    Acta Physica Polonica B, 2010
    Co-Authors: Lance Labun, Johann Rafelski
    Abstract:

    Department of Physics, The University of Arizona, Tucson, 85721 USAUnderstanding physics in domains of Critical (quantum unstable) fieldsrequires investigating the classical and quantum particle dynamics at theCritical Acceleration, ˙u→ 1 [natural units]. This regime of physics remainstoday experimentally practically untested. Particle and light collision ex-periments reaching Critical Acceleration are becoming feasible, in particularapplying available high intensity laser technology. Ultra-relativistic heavyion collisions breach the Critical domain but are complicated by the pres-ence of much other physics. The infamous problem of radiation reactionand the challenging environment of quantum vacuum instability arising inthe high field domain signal the need for a thorough redress of the presenttheoretical framework.PACS numbers: 03.50.De,12.20.-m,12.38.Mh,41.60.-m,41.75.Jv