Magnetism of oxygen deficient perovskite La8−xSrxCu8O20

We have measured muon spin relaxation (μSR) of La8−xSrxCu8O20, an oxygen deficient perovskite, across two magnetic phase transitions at T=Tc1 and Tc2. Static magnetic order was observed below T∼140K, where weak ferromagnetism appears in magnetization measurements (Tc1). No significant change appeared in the μSR static field width at the lower transition temperature Tc2, where an anomaly is seen in the Hall coefficient. The static magnetism thus originates from localized spins presumably in the one-dimensional Cu–O chains.