YCa3(VO)3(BO3)4: A Kagomé Compound Based on Vanadium(III) with a Highly Frustrated Ground State

A new S = 1 kagomé compound based on vanadium(III) is reported. The structure was refined simultaneously against single-crystal neutron and X-ray diffraction data, as a gaudefroyite-type with a new supercell (a′ = 2a + b, b′ = −a − 2b, c′ = c) driven by the ordering of columns of isolated triangular BO33− ions. Low-temperature neutron powder diffraction and magnetic (dc and ac susceptibility) data rule out the presence of long-range magnetic order above at least 1.5 K, but specific heat data suggest that the ground state involves short-range magnetic order, which is frustrated by the coexistence/competition of FM and AFM correlations, together with the characteristic geometric frustration of the kagomé lattice. Magnetic susceptibility data rule out a spin-glass state, pointing to an exotic ground state comparable to the spin-ice or spin-liquid states. This makes YCa3(VO)3(BO3)4 one of the most highly frustrated experimental realizations of the kagomé lattice yet discovered.