μSR Study of Magnetic Order in LTO and LTT Phase of La 2−x M x Cu 1−y Zn y O 4 ( M =Sr, Ba)

Abstract

In order to investigate the origin of so-called 1/8 anomaly in La(Sr,Ba)-214, we have performed μSR experiments for the low-temperature orthorhombic (LTO) and low-temperature tetragonal (LTT) structure phases in La_2−xSr_xCu_1−yZn_yO₄ (LSCO) and La_2−xBa_xCu_1−yZn_yO₄ (LBCO), and decided the magnetic order temperature T_m where μ-spin coherent rotation starts. 1% Zn-substitution depresses magnetic order in the LTT phase of LBCO while it induces or enhances magnetic order in the LTO phase of LSCO. With doping Tm rises first and keeps constant around x=1/8 and decreases in both Zn-substituted LSCO and LBCO. This implies that doped holes are never uniformly distributed on the CuO₂ plane, suggesting the segregation of spin and hole around x=1/8.