Using bulk susceptibility and neutron scattering techniques, we have studied a new frustrated magnet, BaCr9pGa12-9pO19 [BCGO(p)], with 0.4 ≲ p ≲ 0.9. This system is isostructural to SrCr9pGa12-9pO19 [SCGO(p)], in which the magnetic Cr3+ (3d3, s = 3/2) ions form a quasi-two-dimensional triangular lattice of bi-pyramids or kagome-triangle-kagome trilayers. Our bulk susceptibility data exhibit glassy behavior at temperatures much lower than the absolute values of the Curie-Weiss temperature ΘCW ≈ -695(1) K for BCGO(p = 0.902(8)). The frustration index |ΘCW|/Tf is as high as 190 for BCGO(p = 0.902(8)) indicating strong frustration. Our inelastic neutron scattering data on BCGO(p = 0.902(8)) reveal a dispersionless magnetic excitation centered at ℏω = 16.5(1) meV, due to a singlet to triplet excitation of spin s = 3/2 dimers. The spin dimers are formed by Cr3+ ions in two 4fvi layers that lie between 12k-2a-12k (kagome-triangle-kagome) trilayers. These results indicate that BCGO(p) is another good candidate system for a strongly frustrated quasi-two-dimensional magnet.
ASJC Scopus subject areas
- Physics and Astronomy(all)