Abstract
Geometric frustration can produce a non-collinear magnetic state associated with a spin-induced
electric polarization. With geometric frustration on alternating triangular and kagome layers,
CaBaCo4O7 may have one of the largest measured spin-induced polarizations of ∼ 1700 nC/cm2
below its ferrimagnetic transition temperature. Powder diffraction data, magnetization measurements,
and THz absorption frequencies reveal that the spin state of multiferroic CaBaCo4O7 can
be described as a triangular array of c-axis chains with strong coupling within each chain but weak
coupling in the ab plane between chains. Magnetostriction for a set of weak spin bonds in the ab
plane coupling those chains produces the large spin-induced polarization of CaBaCo4O7.
