| We report zero and longitudinal field muon spin relaxation muSR measurements of the spin S=½ antiferromagnetic Heisenberg chain material SrCuO2. Previous muSR experiments by Matsuda and coworkers focused on the magnetic order, which was found to be the manifestation of spin freezing. Here we discuss our muSR results in terms of spin transport, i.e. low energy spin dynamics of the underlying Heisenberg Hamiltonian. We find that in a weak applied magnetic field B the spin-lattice relaxation rate lambda follows a power law λ~B(-n) with n=0.9(3). This result is temperature independent. Within conformal field theory and using the Müller ansatz we identify this with ballistic spin transport in SrCuO2. Furthermore we report studies on the influence of doping/impurities on the magnetic order found for T<~2K. |
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