Observation of an Antiferromagnetic Phase in the Bi₂Sr₂CuO_6+<i>y</i>System by the µ⁺SR Technique

Abstract

We have observed antiferromagnetic ordering in the insulating phase ( x ≥0.50) of the single-CuO 2 -layer (per unit cell) Bi 2 (Sr 1- x La x ) 2 CuO 6+ y system. The Néel temperature increases from 10 K to 140 K with increasing La concentration. In this respect the system behaves like other high- T c copper oxide superconductors. In both x =0.55 and x =0.60 specimens, two hyperfine magnetic fields (45 G and 300 G) were observed at different µ + sites in the crystal.