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  • 75.80.+q  (2)
  • 72.80.Sk  (1)
  • PACS. 74.25.Ha Magnetic properties – 74.72.Jt Other cuprates – 76.60.Cq Chemical and Knight shifts  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    JETP letters 66 (1997), S. 868-872 
    ISSN: 1090-6487
    Schlagwort(e): 72.20.-i ; 72.80.Sk ; 75.80.+q
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The thermal conductivity of the pure and zinc-doped spin-Peierls compound CuGeO3 is investigated for the first time. Characteristic features reflecting the changes in the phonon spectrum of the crystals are observed in the k(T) curves at a transition into the dimerized state in CuGeO3 at T sp =14.2 K and in Cu0.98Zn0.02GeO3 at T sp =10.6 K. Near the spin-Peierls transition temperature T sp the thermal conductivity of Cu0.98Zn0.02GeO3 (k=3 W/m·K) is much less than the thermal conductivity of CuGeO3 (k=21.5 W/m·K).
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1090-6487
    Schlagwort(e): 75.30.Kz ; 75.80.+q
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The longitudinal and transverse magnetostriction λ of the spin-Peierls compound CuGeO3 in the b-c plane is measured in magnetic fields up to 20 T both above and below the transition temperature T sp=14.3K. It is found that for a given crystallographic direction the value of magnetostriction is weakly dependent on the magnetic field direction. In the uniform U phase at T⩾T sp, λ is negative and approximately equal in the b and c directions, while in the dimerized D phase at T〈T sp, λ is positive and λ b 〉λ c . At low temperatures, λ increases sharply at the magnetic-field-induced transition from the dimerized to the magnetic M phase. The experimental data allow estimation of the stress derivatives of the antiferromagnetic intrachain exchange interaction parameter and of the stress dependence of the critical field of the D-Mphase transition.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1434-6036
    Schlagwort(e): PACS. 74.25.Ha Magnetic properties – 74.72.Jt Other cuprates – 76.60.Cq Chemical and Knight shifts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: 63Cu-NMR measurements have been performed on two-leg hole-doped spin ladders Sr14-xCaxCu24O41 single crystals 0 ? x ? 12 at several pressures up to the pressure domain where the stabilization of a superconducting ground state can be achieved. The data reveal a marked decrease of the spin gap derived from Knight shift measurements upon Ca substitution and also under pressure and confirm the onset of low lying spin excitations around P c as previously reported. The spin gap in Sr 2 Ca 12 Cu 24 O 41 is strongly reduced above 20 kbar. However, the data of an experiment performed at P = 36 kbar where superconductivity has been detected at 6.7 K by an inductive technique have shown that a significant amount of spin excitations remains gapped at 80 K when superconductivity sets in. The standard relaxation model with two and three-magnon modes explains fairly well the activated relaxation data in the intermediate temperature regime corresponding to gapped spin excitations using the spin gap data derived from Knight shift experiments. The data of Gaussian relaxation rates of heavily doped samples support the limitation of the coherence length at low temperature by the average distance between doped holes. We discuss the interplay between superconductivity and the spin gap and suggest that these new results support the exciting prospect of superconductivity induced by the interladder tunneling of preformed pairs as long as the pressure remains lower than the pressure corresponding to the maximum of the superconducting critical temperature.
    Materialart: Digitale Medien
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