Experimental Evidence for Static Charge Density Waves in Iron Oxypnictides

The authors acknowledge the ESRF for synchrotron beam time (proposal HC-1468); A. M. acknowledges Andy Fitch for his kind support and experimental assistance during the data collection at the ID22 beam line of ESRF (proposal HC-1468). This work is partially supported by RIDEIRON project (PRIN No. 2012X3YFZ2).