Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons: Spin Systems and Itinerant Magnets - Frustrated Magnets II
TT 20.8: Vortrag
Montag, 31. März 2014, 17:00–17:15, HSZ 304
Hindered magnetic order from multiple dimensionalities in CuP2O6 — •Alexander A. Tsirlin1, Ramesh Nath2, Jörg Sichelschmidt3, Fabien Alet4, and Ioannis Rousochatzakis5 — 1NICPB, Tallinn, Estonia — 2Indian Institute of Science Education and Research, Trivandrum, India — 3MPI CPfS, Dresden, Germany — 4Universite de Toulouse, France — 5IFW Dresden, Germany
We report magnetic properties of CuP2O6, where spin systems of different dimensionalities coexist and lead to a strong suppression of the magnetic ordering transition. This compound features spin planes formed by the Cu1 sites (2D) and spin chains formed by the Cu2 sites (1D), with the antiferromagnetic couplings J2D≃ 40 K and J1D≃ 3 K, respectively. The estimates obtained from density-functional band structure calculations are verified by quantum Monte-Carlo fits to the experimental magnetization data. The magnetic ordering transition at TN≃ 8 K results in the formation of a very weak net moment arising from Dzyaloshinsky-Moriya anisotropy in the Cu1 planes. However, the ESR signal does not vanish below TN. We ascribe this peculiar effect to the drastic difference between the two sublattices: in the weakly coupled 1D sublattice, the ordered moment grows very slowly, hence the behavior of this sublattice is largely paramagnetic even below TN. This physics is captured by a mean-field theory showing that the Néel temperature of CuP2O6 is determined by the geometrical mean value of staggered susceptibilities in the 1D and 2D sublattices.
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