Viktor V. Poltavets

Bulk Magnetic Order in a Two Dimensional Ni1+/Ni2+ (d9/d8) Nickelate, Isoelectronic with Superconducting Cuprates

The Ni1+/Ni2+ states of nickelates have the identical (3d(9)/3d(8)) electronic configuration as Cu2+/Cu3+ in the high temperature superconducting cuprates, and are expected to show interesting properties. An intriguing question is whether mimicking the electronic and structural features of cuprates would also result in superconductivity in nickelates. Here we report experimental evidence for a bulklike magnetic transition in La4Ni3O8 at 105 K. Density functional theory calculations relate the transition to a spin density wave nesting instability of the Fermi surface.

NMR evidence for spin fluctuations in the bilayer nickelate La3Ni2O6

. This materialbelongs to a family of low valence nickel oxides with square planar coordination of the Ni ionsand is isoelectronic to the high temperature superconducting cuprates. Although the three layernickelate compound exhibits a spin-state transition accompanied by antiferromagnetic order, thebilayer material shows no phase transition. The NMR data in the bilayer La