Abstract
We report detailed magnetic, transport, heat-capacity, and neutron-diffraction measurements of Ba5Ru3O12, a compound consisting of isolated Ru3O12 trimers. We show that this system develops long-range antiferromagnetic ordering at TN∼60K without structural distortion or metal-insulator type transition, which is in sharp contrast to other barium ruthenate trimer systems such as 9R−BaRuO3 and Ba4Ru3O10. A complex magnetic structure is revealed which is attributable to the magnetic frustration due to competing exchange interactions between Ru ions on different crystallographic sites within the Ru3O12 trimer and different degree of orbital hybridization on different Ru sites. We have also investigated the magnetic structure of Ba4Ru3O10 for comparisons.
