Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)
MA 20.139: Poster
Dienstag, 28. März 2006, 15:15–19:15, P1
Onset of geometric frustration in the spinels Co(Al1−xCox)2O4 — •N. Tristan1, V. Zestrea1,2, R. Klingeler1, B. Büchner1, and V. Tsurkan2,3 — 1Leibniz-Institute for Solid State and Materials Research IFW Dresden, Postfach 270116, — 2Institute of Applied Physics, Academy of Sciences of Moldova, — 3Experimental Physics V, Center for Electronic
Very recently geometrical frustration has been shown to be an important factor for the MAl2O4 (M=Mn,Fe,Co) spinels, containing magnetic ions solely on the tetrahedral A-sites. The Co3O4 and CoAl2O4 are isostructural normal spinels with close lattice parameters a=8.0834 and 8.1045Ȧ, respectively. Co3O4 is known to be an antiferromagnetic below 40 K, while CoAl2O4 is characterized by a large frustration parameter f=22 and exhibits a spin-glass-like magnetic order below 5K. We present results of an experimental investigation of the structural, magnetic and thermodynamic properties of the solid solutions Co(Al1−xCox)2O4 for 0≤x≤1 with particular attention to compositions close to percolation threshold and onset of the long-range order. The role of the geometrical frustration on the formation of magnetic ground state is discussed.