REZnAl 11 O 19 (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 REZnAl 11 O 19 (RE = Pr–Tb) compounds with space-group P 6 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, PrZnAl 11 O 19 exhibits large magnetic frustration with frustration index f = | θ 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.