P. K. Mang,1 S. Larochelle,2,* A. Mehta,3 O. P. Vajk,2,† A. S. Erickson,1 L. Lu,1 W. J. L. Buyers,4 A. F. Marshall,5 K. Prokes,6 and M. Greven1,3 1Department of Applied Physics, Stanford University, Stanford, California 94305, USA 2Department of Physics, Stanford University, Stanford, California 94305, USA 3Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94309, USA 4National Research Council, Neutron Program for Materials Research, Chalk River Laboratories, Chalk River, Ontario K0J 1J0, Canada 5T. H. Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA 6Hahn-Meitner-Institut, Glienicker Str. 100, Berlin D-14109, Germany (Received 20 December 2003; revised manuscript received 9 March 2004; published 17 September 2004)