REZnAl11O19 (RE = Pr, Nd, Sm-Tb): a new family of ideal 2D triangular lattice frustrated magnets

We report the synthesis, structure and magnetic properties of a new family of rare-earth (RE) based magnetoplumbite-type REZnAl11O19 (RE = Pr-Tb) compounds with space-group P6(3)/mmc. The structural analysis reveals that magnetic RE ions form layers of ideal 2D triangular-lattices in the ab-plane well separated by several nonmagnetic polyhedra layers along the c-axis. The magnetic susceptibilities reveal that the compounds display dominant antiferromagnetic (AFM) exchange interactions and there is no magnetic transition down to 2 K. As a representative, PrZnAl11O19 exhibits large magnetic frustration with frustration index f = |theta(CW)/T-N| > 23 and absence of magnetic order down to 0.43 K, serving as a promising quantum spin liquid candidate. The magnetizations combined with electron spin resonances indicate the distinct anisotropic magnetic behaviors for compounds with different RE ions. These series of compounds provide a modeling system for exploring the novel magnetic phases of RE ions on ideal 2D triangular lattices.