Electronic properties of a distorted kagome lattice antiferromagnetDy3Ru4Al12

Abstract

Electronic properties of ${\mathrm{Dy}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$ (hexagonal crystal structure, Dy atoms form distorted kagome nets) are studied on a single crystal by means of magnetization, neutron diffraction, specific heat, and resistivity measurements. The onset of a long-range magnetic order of Dy moments occurs at 7 K through a first-order phase transition. The compound has a noncollinear antiferromagnetic structure with a propagation vector (1/2 0 1/2). The configuration of the Dy moments is consistent with the monoclinic Shubnikov group ${C}_{c}2/c$. The \ensuremath{\gamma} coefficient in the temperature linear term of the specific heat is strongly enhanced to 500 mJ ${\mathrm{mol}}^{\ensuremath{-}1}$ ${\mathrm{K}}^{\ensuremath{-}2}$ taking into account the localized nature of Dy magnetism. An additional contribution originates from spin fluctuations induced in the $4d$ subsystem of Ru by the exchange field acting from the Dy $4f$ moments. In an applied magnetic field ${\mathrm{Dy}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$ displays magnetization jumps along all crystallographic directions. All the metamagnetic transitions are accompanied by large positive magnetoresistance. The maximum effect (125%--140%) is attained for current along the [100] axis and field along the [120] or [001] axes. The large positive effect is explained by changes in the conduction electron spectra through the jumps as the conduction electrons interact with localized magnetic moments.