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arXiv · 0711.3078

Magnetic-field-induced enhancement of the vortex pinning in the overdoped regime of La$_{2-x}$Sr$_x$CuO$_4$ : Relation to the microscopic phase separation

Yoichi Tanabe·Tadashi Adachi·Keisuke Omori·Hidetaka Sato·Takashi Noji·Yoji Koike
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Abstract

In order to investigate the inhomogeneity of the superconducting (SC) state in the overdoped high-$T_{\rm c}$ cuprates, we have measured the magnetic susceptibility, $χ$, of La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) single crystals in the overdoped regime in magnetic fields parallel to the c-axis up to 7 T on warming after zero-field cooling. It has been found for $x$ = 0.198 and 0.219 that the temperature dependence of $χ$ in 1 T shows a plateau, that is, $χ$ is almost independent of temperature in a moderate temperature-range in the SC state. Moreover, a so-called second peak in the magnetization curve has markedly appeared in these crystals. These results indicate an anomalous enhancement of the vortex pinning and strongly suggest the occurrence of a $microscopic$ phase separation into SC and normal-state regions in the overdoped high-$T_{\rm c}$ cuprates.

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Yoichi Tanabe, Tadashi Adachi, Keisuke Omori, Hidetaka Sato, Takashi Noji, Yoji Koike. 2007-11-20. Magnetic-field-induced enhancement of the vortex pinning in the overdoped regime of La$_{2-x}$Sr$_x$CuO$_4$ : Relation to the microscopic phase separation. https://doi.org/10.1143/jpsj.76.113706

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