UC Irvine

Neutron-diffraction measurements have been taken on single crystals of NdBa2Cu3O6+x to explore the nature of the magnetic order as a function of oxygen concentration x. The Cu-O planes are known to order antiferromagnetically at TN1, with TN1(x0) 450 K. At lower temperatures we find that the oxygen-deficient Cu planes also order magnetically [TN2(x0.1) 80 K], with a large ordered moment of 0.46B and a simple antiferromagnetic sequencing along the c axis. Both ordering temperatures decrease with increasing x, with TN2 being much more sensitive to x than TN1. © 1988 The American Physical Society.