Neutron diffraction study of the magnetic ordering of BaCuO2+x (abstract)

Abstract

Neutron diffraction experiments have been performed in order to study the magnetic ordering of BaCuO2+x. In these measurements unpolarized neutrons and polarized neutrons with full polarization analysis have been utilized. From these measurements it has been determined that BaCuO2+x orders antiferromagnetically below TN=15.0±0.5 K with a magnetic propagating vector κ=[1 1 1]. This structure is commonly referred to as a [πππ] or a G structure. The Cu atoms in the Cu6 ring clusters, located at the (1/4, 1/4, 1/4) positions, order ferromagnetically within these clusters while the clusters themselves order antiferromagnetically. The ordered magnetic moment of each of these Cu atoms is 0.89±0.05 μB at T=4.2 K. No evidence of long-range magnetic ordering of the Cu atoms in the Cu18 clusters, located at the (0, 0, 0) and (1/2, 1/2, 1/2) positions, was found down to a temperature T=2.5 K. The work at Oak Ridge National Laboratory (ORNL) was sponsored by the Division of Materials Sciences, U.S. Department of Energy (DOE). ORNL is managed for the U.S. DOE by Martin Marietta Energy Systems, Inc., under Contract No. DE-AC05-84OR21400. Ames Laboratory is operated for the U.S. DOE under Contract No. W-7405-Eng-82. The work at Ames was supported by the Director for Energy Research, Office of Basic Energy Sciences.