High-oxygen-pressure synthesis, structure and properties of the infinite-chain compound Sr_0.73CuO₂

A new low-dimensional compound has been synthesized at high oxygen pressure PO2 = 2000 bar. X-ray single crystal structure analysis shows that Sr0.73CuO2 has a semi-incommensurate structure consisting of one-dimensional corrugated edge-sharing CuO2 chains alternating with Sr planes. From susceptibility measurements this compound is found to have an antiferromagnetic exchange coupling with a Curie-Weiss temperature of 135 K. A sharp magnetic transition occurs at 10 K which progressively disappears at applied magnetic fields larger than 1 T. While not yet understood this transition could originate from a structural instability.