MAGNETIC TRANSITION IN HIGHLY FRUSTRATED SRCR8GA4O19 - THE ARCHETYPAL KAGOME SYSTEM

Both dc and ac magnetic susceptibility have been carefully measured and analyzed in order to determine the features of the low-temperature magnetic state of the highly frustrated SrCr8Ga4O19 compound. The scaling analysis of the nonlinear part of the dc magnetic susceptibility gives clues that indicate that the nature of the magnetic state below Tf does not correspond to a conventional spin glass. This idea is further confirmed by the study of the dynamic scaling that also differs from what is expected for a conventional spin glass. A progressive change towards a more conventional magnetic ordering below Tf is observed by substituting Ga atoms by Fe atoms in the compound SrCr8Ga4-2xFexO19. For x=1.5, both the scaling analysis of the nonlinear part of the dc magnetic susceptibility and the dynamic scaling seem to indicate that a true spin-glass phase transition does exist at Tf. This change in the magnetic behavior is attributed to the fact that the presence of a magnetic atom in the 4fVI sites as a first neighbor of the Cr atoms, located in the 12k sites, will impose a local preferential direction for the magnetic moments removing somehow the strong intrinsic magnetic frustration of the kagomé lattice. © 1994 The American Physical Society.