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TT: Tiefe Temperaturen
TT 9: Neue und unkonventionelle Supraleiter
TT 9.10: Talk
Tuesday, March 25, 2003, 11:45–12:00, HSZ301
Magnetic order and correlations in a TbNi2B2C single crystal — •A. Kreyssig1, O. Stockert2, E. Ressouche3, J.-U. Hoffmann4, C. Ritter5, B. Grenier3, D. Souptel6, G. Behr6, and M. Loewenhaupt1 — 1TU Dresden, Inst. f. Angew. Physik (IAPD), D-01062 Dresden — 2MPI Chem. Physik fester Stoffe, D-01187 Dresden — 3CEA Genoble, CENG, F-38054 Grenoble — 4Hahn-Meitner-Institut, D-14109 Berlin — 5Institut Laue-Langevin, BP 156, F-38042 Grenoble — 6IFW Dresden, PF 270116, D-01171 Dresden
The tetragonal rare earth nickel borocarbides RNi2B2C show interesting physical properties, especially the coexistence of superconductivity and long range magnetic order. Neutron scattering experiments were performed on the diffractometers D23, ILL Grenoble, and E2, HMI Berlin, using a large TbNi2B2C single crystal. Below TN = 15 K the Tb3+-moments order in a longitudinal modulated antiferromagnetic structure with a temperature dependent incommensurate propagation vector of about (0.545 0 0). At 7 K a lock-in transition of the propagation vector into a nearly commensurate value of (6/11 0 0) occurs. Additionally, intensity at forbidden reflections is observed. An explanation for these effects can be given by a modified magnetic structure with modulations of the magnetic moments in two directions. Diffuse magnetic neutron scattering was investigated between 15 K and 75 K by measuring complete (h 0 l)-planes on E2. The diffuse scattered intensities can be interpreted as the susceptibility of conduction electrons visible through short-range correlations of the Tb3+-moments due to RKKY-interactions.