Ga NMR study of the local susceptibility in kagome-based SrCr8Ga4O19:: Pseudogap and paramagnetic defects

We present the first Ga(4f) NMR study of the Cr susceptibility in the archetype of kagome-based frustrated antiferromagnets, SrCr8Ga4O19. Our major finding is that the susceptibility of the frustrated lattice goes through a maximum around 50 K. Our data also support the existence of paramagnetic clusters of spins, responsible fur the Curie behavior observed in the macroscopic susceptibility at low T. These results set novel features for the constantly debated physics of geometrically frustrated magnets.