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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.15: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

High-field ESR study of the quantum spin magnet CaCu₂O₃ doped with nonmagnetic Zn — •U. Schaufuß, C. Sekar, G. Krabbes, N. Tristan, S.-L. Drechsler, V. Kataev, and B. Büchner — Leibniz Institute for Materials Research IFW Dresden

CaCu₂O₃ is a low-dimensional s = 1/2 antiferromagnet with a structurally well defined two-leg ladder topology. However, no spin gap characteristic of a two-leg S = 1/2-ladder is observed in this material. Instead, CaCu₂O₃ orders antiferromagnetically at T_N = 25 K and exhibits a small magnetic anisotropy gap at T < T_N [1]. Our recent high-field ESR study of a single crystal of CaCu₂O₃ reveals an important role of a few percent of ’extra’ spins residing at the structural imperfections for the low-temperature magnetism of the bulk spin lattice in this compound [1]. To obtain a deeper insight into a complex interplay between the host and the ’extra’ spins we studied static magnetization and high-field ESR of a series of CaCu₂O₃ single crystals doped with nonmagnetic Zn. We discuss the influence of the nonmagnetic defects on the properties of the strongly correlated low-dimensional spin lattice focussing on the doping dependence of T_N and of the anisotropy gap.
[1] M. Goiran at al., cond-mat/0501647.