Magnetic Phase Diagram of Hole-Doped Ca2-xNaxCuO₂Cl₂Cuprate Superconductor

We report on the magnetic phase diagram of a hole-doped cuprate Ca₂₋ₓNaₓCuO₂Cl₂, which is free from buckling of CuO₂ planes, determined by muon spin rotation and relaxation. It is characterized by a quasi-static spin glass-like phase over a range of sodium concentration (0.05≤ x≤ 0.12), which is held between long range antiferromagnetic (AF) phase (x≤ 0.02) and superconducting phase where the system is non-magnetic for x≥ 0.15. The obtained phase diagram qualitatively agrees well with that commonly found for hole-doped high- cuprates, strongly suggesting that the incomplete suppression of the AF order for $x>0.02$ is an essential feature of the hole-doped cuprates.