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TT: Fachverband Tiefe Temperaturen

TT 18: CE: Low-dimensional Systems - Materials 1

TT 18.6: Vortrag

Montag, 14. März 2011, 19:45–20:00, HSZ 201

Low temperature ballistic spin transport in the S=1/2 antiferromagnetic Heisenberg chain compound SrCuO₂ — H. Maeter¹, A.A. Zvyagin^1,2, H. Luetkens³, G. Pascua³, Z. Shermadini³, C. Hess⁴, N. Hlubek⁴, B. Büchner⁴, R. Saint-Matin⁵, A. Revcolevschi⁵, and •H.-H. Klauss¹ — ¹Institut für Festkörperphysik, TU Dresden — ²Institute for Low Temperature Physics and Engineering of the NAS of Ukraine, Kharkov, 61103, Ukraine — ³Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen, Switzerland — ⁴Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden — ⁵Laboratoire de Physico–Chimie de L’Etat Solide, ICMMO, UMR 8182, Universite Paris-Sud, 91405 Orsay, France

For one-dimensional quantum spin chain systems recent experimental and theoretical studies indicate unexpectedly large, in some cases diverging spin and heat transport coefficients. Local probes, like e.g. muon spin relaxation (µSR) can indirectly characterize the spin transport properties of low dimensional systems via the magnetic field dependence of the spin lattice relaxation rate λ(B). For diffusive spin transport λ ∝ B^−0.5 is expected. For the ground state of the isotropic spin-1/2 antiferromagnetic Heisenberg chain the eigenstates of the Heisenberg Hamiltonian dominate the spin transport, which is then ballistic. Using the Müller ansatz λ ∝ B⁻¹ is expected in this case. For SrCuO₂ we find λ ∝ B^−0.9(3). This result is temperature independent for 5 K≤ T ≤ 300 K. Within conformal field theory and using the Müller ansatz we conclude ballistic spin transport in SrCuO₂.