MRSej, Vol. 6, No.1, pp.221-228, 2004
DIFFERENT REGIMES OF STRIPE FLUCTUATIONS IN THE SUPERCONDUCTING CUPRATES
Institute for Technical Physics of the RAS, 420029 Kazan , Russia
The complementary NMR and ESR studies of the frustrated phase separation in different superconducting cuprates are reported. We specially address the temperature dependence of the magnetic fluctuations and discuss their link with the observed superconducting state. It is argued that according to the phase diagram obtained for the lanthanum cuprates the superconducting phase coexists with the developed antiferromagnetic correlations. The observed picture is strongly dependent on the hole doping. In the vicinity of 1/8 doping such a coexistence may be realized in a form of dynamic stripes – the corresponding enhancement of the spin-stiffness reveals the plane character of the spin (and charge) inhomogeneities. Depending on whether these inhomogeneities are pinned or not, one has to distinguish the static and dynamical regimes of stripe fluctuations. With a help of our spin stiffness estimations, the upper threshold values of this quantity critical for the superconducting state were determined. The NMR analysis of the stripe phase local properties made it possible to estimate the local magnetic moment corresponding to antiferromagnetic domains as well as the charge of the domain walls.
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