Ga-NMR local susceptibility of the kagome-based magnet SrCr_9pGa_(12-9p)O_19. A high temperature study

We report a high-$T$ Ga-NMR study in the kagome-based antiferromagnetic compound SrCr${}_{9p}$Ga${}_{12-9p}$O${}_{19}$ ($.81\le p\le .96$), and present a refined mean-field analysis of the high T local NMR susceptibility of Cr frustrated moments. We find that the intralayer kagome coupling is $J=86(6)$ K, and the interlayer coupling through non-kagome Cr moments is $J^{\prime }=69(7)$K\mathrm{.}The$J^{\prime}/J=0.80(1)$ ratio confirms the common belief that the frustrated entity is a pyrochlore slab.