Entropy Balance and Evidence for Local Spin-Singlets in a Kagome-Like Magnet

We have measured the specific heat, C(T), of the S = 3/2 kagome-lattice-containing compound SrCr sub (9p) Ga sub (12-9p) O sub (19). We find little field dependence of the low-temperature C(T), consistent with a low-energy spectrum dominated by many-body singlet excitations. At high temperatures, we recover only ~ 50% of the total Rln4 entropy.