69,71GaNMR in thekagomélattice compoundSrCr9−xGa3+xO19

Abstract

We report the NMR site assignment of ${}^{69,71}\mathrm{Ga}$ in the kagomé lattice compound ${\mathrm{SrCr}}_{9-x}{\mathrm{Ga}}_{3+x}{\mathrm{O}}_{19},$ and discuss the couplings of the different Ga nuclei with Cr moments. We find that $\mathrm{Ga}\mathrm{}\left(4e\right)\mathrm{}$ is dominantly coupled to the triangular plane, and $\mathrm{Ga}\mathrm{}\left(4f\right)\mathrm{}$ is coupled to both the kagomé and triangular planes. The low-temperature behavior of the NMR signal in ${\mathrm{SrCr}}_8{\mathrm{Ga}}_4{\mathrm{O}}_{19}$ suggests that a slowing down of some spin degrees of freedom occurs first on the kagomé plane.