Development of spatial inhomogeneity of internal magnetic field above $T_{ m c}$ in Bi$_2$Sr$_2$Ca$_{1-x}$Y$_x$Cu$_2$O$_{8+\delta}$ observed by longitudinal-field muon-spin-relaxation

摘要

Longitudinal-field muon-spin-relaxation measurements have revealedinhomogeneous distribution of the internal magnetic field at temperatures abovethe bulk superconducting (SC) transition temperature, $T_{\rm c}$, in slightlyoverdoped Bi$_2$Sr$_2$Ca$_{1-x}$Y$_x$Cu$_2$O$_{8+\delta}$. The distributionwidth of the internal magnetic field, $\Delta$, evolves continuously withdecreasing temperature toward $T_{\rm c}$. The origin of the increase in$\Delta$ is discussed in terms of the creation of SC domains in a sample.