  Magnetic susceptibility, NMR, muSR, and inelastic neutron scattering
measurements show that kapellasite, Cu3Zn(OH)6Cl2, a geometrically frustrated
spin-1/2 kagome antiferromagnet polymorphous with the herbertsmithite mineral,
is a gapless spin liquid with frustrated interactions showing unusual dynamic
short-range correlations of non-coplanar cuboc2 type which persist down to 20
mK. The Hamiltonian is determined from a fit of a high-temperature series
expansion to thermodynamical data. The experimental data are compared to
theoretical calculations using the Schwinger-boson approach.
