Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 4: Matter at Low Temperature: Materials
TT 4.5: Vortrag
Montag, 25. Februar 2008, 10:45–11:00, H 3010
AECa4(CoN2)2, AE = Ca, Ba: S = 1 Realization of Shastry-Sutherland Model with Interlayer Interactions — •Alim Ormeci1, Joanna Bendyna1, Peter Höhn1, Rüdiger Kniep1, Johannes Richter2, Walter Schnelle1, and Helge Rosner1 — 1Max-Planck-Institut für Chem. Phys. fester Stoffe, Dresden — 2Institut für Theoretische Physik, Universität Magdeburg, Magdeburg
Recently the tetragonal alkaline-earth nitridocobaltate compounds
BaCa4(CoN2)2 and Ca5(CoN2)2 were synthesized [1]. The
crystal structures of these compounds have in the unit cell two Co layers
separated by c/2 ∼ 6.1 Å. Remarkably each Co layer has the lattice
structure of the Cu2+ spins known from SrCu2(BO3)2. The Co
ions in these compounds have two missing d electrons (s1 d8
configuration) so that they form a spin 1 system. Until now, the S = 1/2
system, SrCu2(BO3)2, has been the only known realization for the
Shastry-Sutherland model. The two nitridocobaltates are suggested as the
first S = 1 realization of this model. Magnetic measurements and
first-principles electronic structure calculations (based on the
full-potential local orbital, FPLO, method) indicate, however, that the
interlayer interactions are non-negligible. Therefore, one has to deal
with a modified model of two Shastry-Sutherland layers coupled to one
another. Results of first-principles and model Hamiltonian calculations
will be compared with experimental data, and the implications will be
discussed.
[1] J.K.Bendyna, P.Höhn, R.Kniep, Z. Kristallogr. NCS
222 (2007), CSD no. 409920 and 409921.