Tommaso Roscilde, Rong Yu, and Stephan Haas
Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484
The possibility of inducing novel quantum phases in low-dimensional quantum systems through lattice disorder has challenged both theory and experiment for decades. We here report numerical evidence of a novel interplay between quantum fluctuations and geometric randomness in two-dimensional antiferromagnets. The general picture is the emergence of a novel quantum-disordered phase between the conventional phases divided by the percolation threshold of the lattice. In particular, we show that inhomogeneous bond-dilution of the square-lattice S = 1 / 2 antiferromagnet leads to the occurrence of a novel infinite family of two-dimensional geometrical structures with a spin-liquid ground state 1 . In addition, site dilution of spin-gap antiferromagnets in their field-induced ordered phase leads to quantum localization of the triplet quasiparticles that condense in the ground state, leading to a novel correlated
Anderson insulating phase that extends well below the lattice percolation threshold 2 .
1 R. Yu, T. Roscilde, and S. Haas, cond-mat/0410041.
2 T. Roscilde and S. Haas, in preparation.
Sorting category: Ce Magnetism and properties of solids
Keywords: Quantum magnets, percolation, spin liquids, localization
LT1981