Magnetism and superconductivity in dopedLa2CuO4

The temperature (T) dependence of magnetic susceptibility (χ) in (${\mathrm{La}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{M}}_{\mathrm{x}}$ ${)}_2$ ${\mathrm{CuO}}_4$ (M=Sr,Ba) is examined for T<580 K. A broad peak (${\chi }_{\max )}$ in the χ-T curve, already reported for a Sr-doped system, is also observed in a Ba-doped one. The temperature exhibiting ${\chi }_{\max }$ decreases with a linear dependence on x and tends rapidly to zero at around x=$x_c$ ($x_c$≃0.12 for M=Sr and ∼0.1 for M=Ba). For x≳$x_c$, the χ monotonically increases with lowering T over the entire T range examined. In both systems, the superconductivity is found to be remarkably suppressed above $x_c$. .AE