%0 Journal Article
%T Anisotropic spin freezing in the S=1/2 zigzag ladder compound SrCuO2
%A I. A. Zaliznyak
%A C. Broholm
%A M. Kibune
%A M. Nohara
%A H. Takagi
%J Physics
%D 1998
%I arXiv
%R 10.1103/PhysRevLett.83.5370
%X Using magnetic neutron scattering we characterize an unusual low temperature phase in orthorhombic SrCuO2. The material contains zigzag spin ladders formed by pairs of S=1/2 chains (J=180 meV) coupled through a weak frustrated interaction |J'|<0.1J. At T<Tc1=5.0(4)K an elastic peak develops in a gapless magnetic excitation spectrum indicating spin freezing on a time scale larger than 200 picoseconds. While the frozen state has long range commensurate antiferromagnetic order along the chains with the correlation length exceeding 200 lattice periods along the c-axis and a substantial correlation length of 60(25) spacings along the a-axis perpendicular to the zigzag plane, only 2 lattice units are correlated along the b-axis which is the direction of the frustrated interactions. The frozen magnetic moment of each Cu ion is very small, 0.033(7) Bohr magneton even at T=0.35K, and has unusual temperature dependence with a cusp at Tc2=1.5K reminiscent of a phase transition. We argue that slow dynamics of stripe-like cooperative magnetic defects in tetragonal a-c planes yield this anisotropic frozen state.
%U http://arxiv.org/abs/cond-mat/9812440v3