$^{139}$La NMR in La$_{4}$Ni$_{3}$O$_{8}$: a possible analog to the cuprate high temperature superconductors

The Ni$^{1+}$/Ni$^{2+}$ states in the nickelates have identical electronic configurations as Cu$^{2+}$/Cu$^{3+}$ in the high temperature superconducting cuprates (3d$^{9}$/3d$^{8})$, and may exhibit similar properties. However, the Ni$^{1+}$ state is rare and cannot be easily stabilized. Recently, Martha Greenblatt and collaborators at Rutgers University have succeeded in growing a family of such compounds, Ln$_{n+1}$Ni$_{n}$O$_{2n+2}$ with a layered structure similar to the cuprates. The La$_{4}$Ni$_{3}$O$_{8}$ compound is particularly interesting as it undergoes an antiferromagnetic transition at T$_{N}$ = 100 K. We have done La NMR on powder samples to investigate the nature of this phase. Our spin lattice relaxation rate measurements clearly reveal a second order electronic phase transition similar to that observed in other antiferromagnets. Although we found clear signatures of changes to the spectra below T$_{N}$, we are unable to assign these changes to the presence of an internal field from the antiferromagnetic structure, or changes to the electric field gradient at the La site.