Dielectric signature of charge order in lanthanum nickelates P. Sippel, S. Krohns, E. Thoms, E. Ruff, S. Riegg, H. Kirchhain, F. Schrettle, A. Reller, P. Lunkenheimer and A. Loidl Eur. Phys. J. B, 85 7 (2012) 235 Published online: 05 July 2012 DOI: 10.1140/epjb/e2012-30183-2