Title: Effective One-Dimensional Coupling in the Highly-Frustrated Square-Lattice Itinerant Magnet CaCo$_{\mathrm{2}-y}$As$_{2}$,
Abstract: Inelastic neutron scattering measurements on the itinerant antiferromagnet
(AFM) CaCo$_{\mathrm{2}-y}$As$_{2}$ at a temperature of 8 K reveal two
orthogonal planes of scattering perpendicular to the Co square lattice in
reciprocal space, demonstrating the presence of effective one-dimensional spin
interactions. These results are shown to arise from near-perfect bond
frustration within the $J_1$-$J_2$ Heisenberg model on a square lattice with
ferromagnetic $J_1$, and hence indicate that the extensive previous
experimental and theoretical study of the $J_1$-$J_2$ Heisenberg model on
local-moment square spin lattices should be expanded to include itinerant spin
systems.