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  • 1
    Electronic Resource
    Electronic Resource
    Spin-flip rate of excitonic magnetic polarons in Cd1−xMnxTe/Cd1−yMgyTe quantum wells (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6457-6459 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The lifetime of excitons in Cd1−xMnxTe/Cd1−yMgyTe single quantum wells was investigated by time-resolved photoluminescence spectroscopy. Spin-flips between dark and bright excitons remarkably change the excitonic lifetime yielding a two-exponential decay in the photoluminescence intensity. The temperature dependence of the two decay times shows that the spin-flip rate depends strongly on the formation of excitonic magnetic polarons. By forming polarons, the spin-flip rate from dark excitons to bright excitons is reduced effectively by the spin- barriers of the polarized Mn ions, which extends significantly the luminescence decay time. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372737
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  • 2
    Electronic Resource
    Electronic Resource
    Transient behavior of the excitonic magnetic polarons in Cd1−xMnxTe epilayers (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6454-6456 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a study of the dynamics of the excitonic magnetic polarons in Cd1−xMnxTe epilayers. The transient photoluminescence measured by a streak camera under resonant excitation is analyzed with a special attention devoted to line shape of the emission signal. A nonradiative spectral region is observed in zero field and is strongly suppressed in a field of 6 T. This observation is understood to be directly related to the alignment of the Mn2+ spins and is therefore closely related to the formation of magnetic polarons. A few Mn spins are found to be aligned already within 10 ps, but the total Mn spin polarization in the sample is found to increase exponentially with a rise time of 37 ps in Cd0.73Mn0.27Te epilayers. Furthermore, the values of 19.2 and 12.4 meV were determined for the energies of the excitonic magnetic polarons in Cd0.73Mn0.27Te and Cd0.79Mn0.21Te epilayers, respectively. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372736
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  • 3
    Electronic Resource
    Electronic Resource
    Asymmetric luminescence line shape and exciton energy relaxation in Zn1−x−yMgxCdySe epilayers (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3494-3496 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The asymmetric line shape of the transient photoluminescence (PL) spectra of high-quality Zn1−x−yMgxCdySe epilayers is deconvoluted to a narrow and a broad Gaussian peak at each time delay. The fitted energy difference between the two peaks corresponds to one longitudinal optical (LO) phonon energy. We assign the narrow peak to the recombination of free excitons (FXs) and the broad peak to the recombination of excitons localized in the broad band tail characteristic for this quaternary compound. The broad PL peak is found to arise from the energy relaxation of the FX at the exciton mobility edge to the localized states by LO phonon emission. Therefore, the population peak of the localized excitons is formed at one LO phonon energy below the FX for all times after the laser excitation. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125366
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  • 4
    Electronic Resource
    Electronic Resource
    Time-resolved magneto-optical experiments in Cd1−xMnxTe/ZnTe multiple quantum wells (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5938-5940 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical pump-probe experiments were performed in Cd0.9Mn0.1Te/ZnTe multiple quantum wells to study the dynamics of the exciton magnetic polaron in this material. Two transient absorptions of opposite sign were observed. The first signal is negative and indicates the decrease of optical absorption, as the excitons are approaching saturation. The second signal is positive and is interpreted as the absorption of "new excitons" after the initial excitons created by the pump pulse have decayed leaving behind a magnetic polarized Mn environment. The spin relaxation time of the Mn ions has been determined to be 601 ps. Finally, we discuss the effect of the polaron–polaron interaction, relevant in our experiment because we saturate the excitons in the quantum wells. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369997
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  • 5
    Electronic Resource
    Electronic Resource
    Novel magnetic relaxation effects in superconducting UPt"3 single crystals
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 185-189 (1991), S. 2625-2626 
    Details
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0921-4534(91)91435-7
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  • 6
    Electronic Resource
    Electronic Resource
    Flux dynamics and low-field magnetic properties of the heavy-fermion superconductor CeCu2Si2 (1993)
    Springer
    Journal of low temperature physics 90 (1993), S. 15-53 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Strong flux creep effects are observed in CeCu2Si2 at low magnetic inductions and temperatures in the range 6 mK〈T〈T c . Measurements of flux creep in single crystal as well as polycrystalline specimens show that the magnetization in CeCu 2 Si 2 decays following a power law time dependence of the typeM(t)∝t −α for 1〈t〈10 5 sec, where the exponent a ranges between 0.015 and 0.06. The activation energy values obtained from the relaxation rates are around 2–3 meV. The flux creep data give clear evidence of the existence of different types of pinning centers in CeCu 2 Si 2 : a large number of shallow potential barriers that characterize the vortex dynamics at short times and few strong pinning centers responsible for the long-time relaxation behavior. Quantum tunneling of flux lines through weak pinning centers probably gives rise to the non-thermally activated relaxation observed at the lowest temperatures. The physical origin of weak and strong pinning centers in CeCu 2 Si 2 is discussed. From isothermal dc magnetization measurements we estimate the lower critical fieldH c1 as well as the critical current densityJ c . TheH c1 versusT curve shows an anomalous positive curvature for temperatures close toT c .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00682009
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