Magnetic correlations in YBaCo4O7 on kagome and triangular lattices

Abstract

Magnetic correlation in ${\mathrm{YBaCo}}_{4}{\mathrm{O}}_{7}$ with kagome and triangular lattices was studied through inelastic-neutron-scattering measurements on a single crystal sample. The broad magnetic excitation was observed below 45 meV and showed dispersions both within the $c$ plane and along the $c$ axis. The wave vector with the minimum energy of the magnetic excitation was totally different from the magnetic Bragg point. Our analysis with the first-moment-sum rule suggests that Co ions in ${\mathrm{YBaCo}}_{4}{\mathrm{O}}_{7}$ form a unique three-dimensional network with the geometrically frustration.