TY - JOUR
T1 - Anomalous enhancement of vortex pinning and microscopic phase separation in the overdoped regime of La2-xSrxCuO4
AU - Tanabe, Y.
AU - Adachi, T.
AU - Sato, H.
AU - Omori, K.
AU - Koike, Y.
PY - 2009
Y1 - 2009
N2 - Our previous study of the magnetic susceptibility, χ, on zero-field and field cooling and magnetization-hysteresis-loop (MHL) for La 2-xSrxCuO4 (LSCO) single crystals with x 0.178 - 0.261 has suggested that a microscopic phase separation into superconducting (SC) and normal-state regions takes place in the overdoped regime of LSCO. In order to clarify the onset hole-concentration where the microscopic phase separation appears, we have carried out χ measurements on zero-field and field cooling and MHL measurements for LSCO single crystals with x 0.125 and 0.147. From the χ measurements in a low magnetic field on field cooling, absolute values of χ at 2 K, |χ2k|, in x 0.125 and 0.147 have been found to be smaller than that of x 0.178, which can be understood in terms of the vortex-pinning effect around twin boundaries in a crystal. Neither two-step SC transition in χ vs- T in a moderate field on zero-field cooling nor second magnetization peak in MHL has been observed in x 0.125, while both characteristics have been observed in x 0.147. These results imply no enhancement of the vortex pinning in a moderate field-range and therefore suggest the existence of a homogeneous superconducting state in x 0.125. Accordingly, it is concluded that the onset hole-concentration of the microscopic phase separation is located between x 0.125 and 0.147.
AB - Our previous study of the magnetic susceptibility, χ, on zero-field and field cooling and magnetization-hysteresis-loop (MHL) for La 2-xSrxCuO4 (LSCO) single crystals with x 0.178 - 0.261 has suggested that a microscopic phase separation into superconducting (SC) and normal-state regions takes place in the overdoped regime of LSCO. In order to clarify the onset hole-concentration where the microscopic phase separation appears, we have carried out χ measurements on zero-field and field cooling and MHL measurements for LSCO single crystals with x 0.125 and 0.147. From the χ measurements in a low magnetic field on field cooling, absolute values of χ at 2 K, |χ2k|, in x 0.125 and 0.147 have been found to be smaller than that of x 0.178, which can be understood in terms of the vortex-pinning effect around twin boundaries in a crystal. Neither two-step SC transition in χ vs- T in a moderate field on zero-field cooling nor second magnetization peak in MHL has been observed in x 0.125, while both characteristics have been observed in x 0.147. These results imply no enhancement of the vortex pinning in a moderate field-range and therefore suggest the existence of a homogeneous superconducting state in x 0.125. Accordingly, it is concluded that the onset hole-concentration of the microscopic phase separation is located between x 0.125 and 0.147.
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U2 - 10.1088/1742-6596/150/5/052266
DO - 10.1088/1742-6596/150/5/052266
M3 - Article
AN - SCOPUS:77952517546
VL - 150
JO - Journal of Physics: Conference Series
JF - Journal of Physics: Conference Series
SN - 1742-6588
IS - 5
M1 - 052266
ER -