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

Abstract

We have measured the specific heat $C\left(T\right)$ of the $S=\frac{3}{2}$ Kagomé-lattice-containing compound $\mathrm{SrCr}{}_{9p}\mathrm{Ga}{}_{12-9p}\mathrm{O}{}_{19}$. We find little field dependence of the low-temperature $C\left(T\right)$, consistent with a low-energy spectrum dominated by many-body singlet excitations. At high temperatures, we recover only $\sim 50\%$ of the total $R\ln 4$ entropy.