title: Unconventional magnetic correlations in DyB2C and HoB2C.
abstract: Layered borocarbides RB2C (R=Dy, Ho, and Er) have been studied by powder neutron diffraction at 2-30 K. ErB2C has two-sublattice antiferromagnetic order below T(N)=16.3 K, but DyB2C and HoB2C show a coexistence of a conventional canted k=(000) ferromagnetic structure and unconventional magnetic correlations. The k=(000) phase orders at T(c)=8.5 K (DyB2C) and 7.1 K (HoB2C), but low-Q diffraction peaks from the unconventional correlations appear above T(c) with different critical temperatures for different peaks: at 8, 10.5, and 15.7 K for HoB2C. This scattering is fitted as diffraction from a Warren-type random magnetic layer lattice and may result from quadrupolar interactions between R3+ spins.
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: van Duijn
authors.forename: J P
authors.initials: JP
authors.lastname: Attfield
authors.forename: R
authors.initials: R
authors.lastname: Watanuki
authors.forename: K
authors.initials: K
authors.lastname: Suzuki
authors.forename: R K
authors.initials: RK
authors.lastname: Heenan