We have studied incommensurate spin ordering in single crystal underdoped La_{2-x}Ba_{x}CuO_{4} with x~0.08, 0.05 and 0.025 using neutron scattering techniques. Static incommensurate magnetic order is observed in the La_{2-x}Ba_{x}CuO_{4} (x=0.05 and 0.025) compounds with ordering wavevectors which are rotated by 45 degree about the commensurate (0.5,0.5,0) position, with respect to that in the superconducting x=0.08 material. These spin modulations are one dimensional in the x=0.05 and 0.025 samples, with ordering wavevectors lying along the orthorhombic b* direction. Such a rotation in the orientation of the static spin ordering as a function of increasing Ba doping, from diagonal to collinear, is roughly coincident with the transition from an insulating to a superconducting ground state and is similar to that observed in the related La_{2-x}Sr_{x}CuO_{4} system. This phenomenon is therefore a generic property of underdoped La-214 cuprates.
@article{arxiv.0712.3832,
title = {Diagonal and Collinear Incommensurate Spin Structures in underdoped La$_{2-x}$Ba$_{x}$CuO$_{4}$},
author = {S. R. Dunsiger and Y. Zhao and B. D. Gaulin and Y. Qiu and P. Bourges and Y. Sidis and J. R. D. Copley and A. B. Kallin and E. M. Mazurek and H. A. Dabkowska},
journal= {arXiv preprint arXiv:0712.3832},
year = {2009}
}