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TT: Fachverband Tiefe Temperaturen

TT 5: CE: Low-dimensional Systems - Materials 1

TT 5.3: Vortrag

Montag, 22. März 2010, 14:45–15:00, H18

Finite size effects and magnetic order in the spin-1/2 honeycomb lattice compound InCu_2/3V_1/3O₃ — •M. Yehia¹, E. Vavilova^1,2, U. Löw³, A. Möller^4,5, T. Taetz⁵, R. Klingeler¹, V. Kataev¹, and B. Büchner¹ — ¹Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden, Germany — ²Zavoisky Physical Technical Institute, Russian Academy of Sciences, 420029 Kazan, Russia — ³Technische Universität Dortmund, Theoretische Physik I, 44221 Dortmund, Germany — ⁴University of Houston, Department of Chemistry and Texas Centre for Superconductivity Houston, TX 77204, USA — ⁵Institut für Anorganische Chemie, Universität zu Köln, 50939 Köln, Germany

A two dimensional spin honeycomb lattice on the basis of InCu_2/3V_1/3O₃ was studied by means of high field electron spin resonance, nuclear magnetic resonance and magnetic susceptibility. Previous structural studies suggest the occurrence of uncorrelated finite size in-plane domains, which is expected to inhibit long range magnetic order. Surprisingly, ESR data reveal the development of two collinear AFM sublattices below ∼20 K whereas NMR results show the presence of the staggered internal field. This is consistent with the magnetization data which implies a reorientation of the spin sublattices at ∼ 5.7 T. Quantum Monte-Carlo calculations of spin clusters of the coupled honeycomb spin planes indicate the development of the staggered magnetization at a finite temperature. This may explain the occurrence of the AFM state in InCu_2/3V_1/3O₃ despite unfavorable for magnetic order structural effects.