title: Crossover from incommensurate to commensurate magnetic orderings in CoCr(2)O(4).
abstract: The conical spin order of multiferroic CoCr(2)O(4) has been studied by a neutron diffraction to investigate its magnetic phase transitions at temperatures below 40 K. Magnetic order of a spiral spin component with an incommensurate propagation vector of (0.63, 0.63, 0) was observed at 26 K, while at 14.5 K, the incommensurate conical spin order showed a transition into the fixed commensurate propagation vector of (2/3,2/3,0). In addition, two satellite peaks with propagation vectors of (0.035, 0, 0) and (0, 0.035, 0) from the commensurate vector were observed. The widths of these peaks indicate a long-range magnetic order. This new magnetic configuration below 14.5 K may lead to a new model of multiferroic behavior differing from the well-known spin-current model for magnetic ferroelectricity.
authors.affiliation: Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: L J
authors.initials: LJ
authors.lastname: Chang
authors.forename: D J
authors.initials: DJ
authors.lastname: Huang
authors.forename: W-H
authors.initials: WH
authors.lastname: Li
authors.forename: S-W
authors.initials: SW
authors.lastname: Cheong
authors.forename: W
authors.initials: W
authors.lastname: Ratcliff
authors.forename: J W
authors.initials: JW
authors.lastname: Lynn