Spin density wave induced disordering of the vortex lattice in   superconducting La$_{2-x}$Sr$_x$CuO$_4$
  We use small angle neutron scattering to study the superconducting vortex lattice in La$_{2-x}$Sr$_x$CuO$_4$ as a function of doping and magnetic field. We show that near optimally doping the vortex lattice coordination and the superconducting coherence length $\xi$ are controlled by a van-Hove singularity crossing the Fermi level near the Brillouin zone boundary. The vortex lattice properties change dramatically as a spin-density-wave instability is approached upon underdoping. The Bragg glass paradigm provides a good description of this regime and suggests that SDW order acts as a novel source of disorder on the vortex lattice. 
J. Chang, J. S. White, M. Laver, C. J. Bowell, S.P. Brown, A.T.   Holmes, L. Maechler, S. Strassle, R. Gilardi, S. Gerber, T...
cond-mat.supr-con