Orbital degeneracy removed by charge order in triangular antiferromagnet AgNiO2 - Condensed Matter > Strongly Correlated ElectronsReport as inadecuate




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Abstract: We report a high-resolution neutron diffraction study on theorbitally-degenerate spin-1-2 hexagonal antiferromagnet AgNiO2. A structuraltransition to a tripled unit cell with expanded and contracted NiO6 octahedraindicates root(3) x root(3) charge order on the Ni triangular lattice. Thissuggests charge order as a possible mechanism of lifting the orbital degeneracyin the presence of charge fluctuations, as an alternative to Jahn-Tellerdistortions. A novel magnetic ground state is observed at base temperatureswith the electron-rich S = 1 Ni sites arranged in alternating ferromagneticrows on a triangular lattice, surrounded by a honeycomb network of non-magneticand metallic Ni ions. We also report first-principles band-structurecalculations that explain microscopically the origin of these phenomena.



Author: E. Wawrzynska, R. Coldea, E.M. Wheeler, I.I. Mazin, M.D. Johannes, T. Sorgel, M. Jansen, R.M. Ibberson, P.G. Radaelli

Source: https://arxiv.org/







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