Low-energy singlet dynamics of spin-1/2 Kagome Heisenberg antiferromagnets and low-temperature features in the specific heat of Kagome clusters

摘要

We suggest a new approach for describing the low-energy sector of spin-(1)/(2) Kagome Heisenberg antiferromagnets (KAFs). The Kagome lattice is represented as a set of blocks (stars) arranged in a triangular lattice. Each of these stars has two degenerate singlet ground states. It is shown using symmetry considerations that the KAF lower singlet band is made by inter-star interaction from these degenerate states. The general form of the effective Hamiltonian describing this band is established. Low-T peculiarities in the specific heat of Kagome clusters are also discussed.