Dresden 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

MA: Magnetismus

MA 4: Kondo / Schwer-Fermionen / Quasi-Niedrigdimensionale Systeme (gemeinsam mit TT)

MA 4.4: Vortrag

Montag, 24. März 2003, 11:00–11:15, HSZ/405

Elastic Neutron Diffraction Study of the Long-Range Antiferromagnetic Ordering in the S=1/2 Quantum Chain System CuSb₂O₆ — •R. K. Kremer¹, B. J. Gibson¹, A. Das¹, A. V. Prokofiev², W. Assmus², and B. Ouladdiaf³ — ¹MPI für Festkörperfirschung, Stuttgart, Germany — ²Physikalisches Institut, J. W. Goethe Universität, Frankfurt, Germany — ³Institute Laue-Langevin, Grenoble Cedex, France

CuSb₂O₆ crystallizes with a distorted variant of the tri-rutile structure type with Cu²⁺ ions arranged in square planar nets being structurally well separated from each other by Sb-O building blocks. We have investigated the magnetic susceptibility and the heat capacity and carried out an elastic neutron diffraction study on chemical vapour transport grown single crystals in order to establish the magnetic structure. The magnetic susceptibility is characterized by a broad maximum centered at 60K indicating short-range ordering effects due to low-dimensional magnetic behaviour. The temperature dependence of the magnetic susceptibility fits very well to the model of a S=1/2 uniform Heisenberg chain with nearest neighbour coupling with an exchange constant of 98(1) K. A kink in the susceptibility and a λ-type anomaly in the heat capacity at 8.6K mark the onset of long-range ordering due to interchain coupling. By elastic neutron diffraction measurements we have established the low-temperature nuclear structure and the ordered antiferromagnetic arrangement of the Cu moments at 2K. Implications of our results with respect to possible Cu - Cu superexchange pathways via oxygen atoms are discussed.