title: Valence bond glass phase in dilute kagome antiferromagnets.
abstract: We present a theory for site dilution in the kagome lattice Heisenberg model. The presence of an empty site leads to strong singlet bonds opposite to the impurity. It also creates a free spin which delocalizes near the impurity. Finite impurity concentration leads to a valence bond glass phase with no spin gap, large spin susceptibilities, linear specific heat due to two-level systems, as well as singlet and triplet excitations that decompose into kink-antikink pairs. It provides a framework for a comprehensive understanding of thermodynamic, neutron, and Raman measurements in the herbertsmithite material ZnCu3(OH)6Cl2, including recently reported H/T and omega/T scaling.
authors.affiliation: University of California Davis, Davis, California 95616, USA.
authors.forename: R R P
authors.initials: RR
authors.lastname: Singh