Ferrodistorsive orbital ordering in the layered nickelate NaNiO2:: A density-functional study -: art. no. 10A314

The electronic structure and magnetism in the sodium nickelate NaNiO2 in the low-temperature phase is studied from density-functional calculations using the linear muffin-tin orbitals method. An antiferromagnetic solution with a magnetic moment of 0.7 mu(B) per Ni ion is found. A ferrodistorsive orbital ordering is shown to occur due to the Jahn-Teller distortion around the Ni+3 ion in agreement With the orbital ordering inferred from neutron diffraction. While the intralayer exchange is ferromagnetic, the interlayer exchange is weakly antiferromagnetic, mediated by a long Ni-O-Na-O-Ni superexchange path. (c) 2005 American Institute of Physics.