Charge stripe glasses in La<Subscript>2-x</Subscript>Sr<Subscript>x</Subscript>NiO<Subscript>4</Subscript> for 0.20 > x > 0.25

We present high resolution X-ray measurements characterising the charge stripe order state in the La<Subscript>2-x</Subscript>Sr<Subscript>x</Subscript>NiO<Subscript>4</Sub script> system with x=0.20, 0.225 and 0.25. We find that in the x=0.20, 0.225 and 0.25 systems the charge stripe order exists in a charge stripe glass characterised by weak, poorly correlated incommensurate charge stripes in contrast to the strong well correlated charge stripes in the commensurate x=1/3 system. No stabilisation of the charge order was observed at the next possible commensurate value of ε= 0.25. A comparison with high energy X-ray measurements suggested that the charge order may exist in a charge stripe glass in the bulk in the doping region x=0.20 - 0.33. Finally at low temperature there was an initial increase in the intensity and correlation not observed with neutron measurements and it appears to be an effect that X-rays are sensitive to but neutrons are not. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005