Intrinsic Susceptibility and Bond Defects in the Novel Two Dimensional Frustrated AntiferromagnetBa2Sn2ZnCr7pGa10−7pO22

We present microscopic and macroscopic magnetic properties of the highly frustrated antiferromagnet ${\mathrm{Ba}}_2{\mathrm{Sn}}_2{\mathrm{ZnCr}}_{7p}{\mathrm{Ga}}_{10-7p}{\mathrm{O}}_{22}$, respectively, probed with NMR and SQUID experiments. The $T$ variation of the intrinsic susceptibility of the ${\mathrm{Cr}}^{3+}$ frustrated Kagomé bilayer, ${\chi }_{\mathrm{Kag}}$, displays a maximum around 45 K. The dilution of the magnetic lattice has been studied in detail for $0.29\le p\le 0.97$. Novel dilution independent defects, likely related with magnetic bond disorder, are evidenced and discussed. We compare our results to ${\mathrm{SrCr}}_{9p}{\mathrm{Ga}}_{12-9p}{\mathrm{O}}_{19}$. Both bond defects and spin vacancies do not affect the average susceptibility of the Kagomé bilayers.