title: 17O NMR study of q = 0 spin excitations in a nearly ideal S = 1 / 2 1D Heisenberg antiferromagnet, Sr2CuO3, up to 800 K.
abstract: We used 17O NMR to probe the uniform (wave vector q = 0) electron spin excitations up to 800 K in Sr2CuO3 and separate the q = 0 from the q = +/-pi / a staggered components. Our results support the logarithmic decrease of the uniform spin susceptibility below T approximately 0.015J, where J = 2200 K. From measurement of the dynamical spin susceptibility for q = 0 by the spin-lattice relaxation rate 1/T(1), we demonstrate that the q = 0 mode of spin transport is ballistic at the T = 0 limit, but has a diffusion-like contribution at finite temperatures even for T<<J.
authors.affiliation: Department of Physics, MIT, Cambridge, Massachusetts 02139 and Center for Materials Science and Engineering, MIT, Cambridge, Massachusetts 02139.
authors.forename: K R
authors.initials: KR
authors.lastname: Thurber
authors.forename: A W
authors.initials: AW
authors.lastname: Hunt
authors.forename: T
authors.initials: T
authors.lastname: Imai
authors.forename: F C
authors.initials: FC
authors.lastname: Chou