Crystal and magnetic structure of Li2CuO2

Abstract

The crystal structure of Li2CuO2 has been reinvestigated and its magnetic structure solved by neutron powder diffraction. The crystal structure, according to an earlier work, is adequately described in the space group Immm. The copper atoms constituting the structural chains are coupled ferromagnetically, giving rise to ferromagnetic layers perpendicular to the c axis. The layers are coupled antiferromagnetically. The magnetic structure has a propagation vector k=[001] and is colinear with spin directions along the a axis and well described by the magnetic mode Ax (Shubnikov group: Ipmm'm'). The magnetic moment of copper atoms at 1.5 K is 0.96(4)microB, which is very close to the saturation moment of spin only Cu+2 (d9). Contrary to the antiferromagnetic parents of high Tc superconductors, the small zero-point reduction of the magnetic moment in Li2CuO2 supports a 3D behaviour of the magnetic interactions.