Complex Magnetic Order in the Kagome Staircase Compound Co3V2O8
01 July 2006
Co3V2O8 (CVO) has a new type of geometrically frustrated magnetic lattice, a Kagome staircase, where the full frustration of a conventional Kagome lattice is partially relieved. The crystal structure consists of two inequivalent (magnetic) Co sites, one-dimensional chain of Co(2) spine sites, linked by Co(1) cross-tie sites. Neutron powder diffraction has been used to solve the basic magnetic and crystal structures of this system, while polarized and unpolarized single crystal diffaction measurements have been used to reveal a rich variety of incommensurate phases, interspersed with lock-in transitions to commensurate phases. CVO initially orders magnetically at 11.3 K into an incommensurate, transversely polarized, spin density wave state, with wave vector k = (0,delta,0) with delta = 0.55 and the spin direction along the a axis. Delta is found to decrease monotonically with decreasing temperature, and then it locks into a commensurate antiferromagnetic structure with delta = 1/2 for 6.9