Simon A. J. Kimber, Mark S. Senn, Simone Fratini, Hua Wu, Adrian H. Hill, Pascal Manuel, J. Paul Attfield, Dimitri N. Argyriou, and Paul. F. Henry, Physical Review Letters 108 (2012), 217205 We show that the valence electrons of Ba 3 NaRu 2 O 9 , which has a quasimolecular structure, completely crystallize below 210 K. Using an extended Hubbard model,Read more
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Mark S. Senn, Ingo Loa, Jon P. Wright, and J. Paul Attfield, Phys. Rev. B 85 (2012), 125119 Electronic structure calculations of the Verwey ground state of magnetite, Fe 3 O 4 , using density functional theory with treatment of on-site Coulomb interactions (DFT+U scheme), are reported. These calculations use the recently published experimental crystal structure coordinatesRead more
MS Senn, JP Wright, JP Attfield, Nature 481 (2012), 173-176 The mineral magnetite (Fe3O4) undergoes a complex structural distortion and becomes electrically insulating at temperatures less than 125 kelvin. Verwey proposed in 1939 that this transition is driven by a charge ordering of Fe2+ and Fe3+ ions, but the ground state of the low-temperature phaseRead more
Mark S. Senn, Simon A. J. Kimber, Angel M. Arevalo Lopez, Adrian H. Hill, and J. Paul Attfield, Physical Review B 87 (13), 134402 The magnetic and crystal structures of the title materials have been investigated using high-resolution neutron and synchrotron x-ray powder diffraction. Ferromagnetic Ru dimers are observed in the spin-ordered ground states ofRead more