Specific Heat and Magnetic Susceptibility of Ising-Like Anisotropic Heisenberg Model on Kagome Lattice

The specific heat and magnetic susceptibility of a spin-1/2 Ising-like anisotropic Heisenberg model (IAHM) on a kagome lattice are investigated by an exact diagonalization method for small clusters up to 18 spins with periodic boundary conditions. The enhancement of magnetic susceptibility from the Curie–Weiss law and the peak structure of specific heat at intermediate temperatures are attributed to a longitudinal (classical) spin fluctuation, and the steep decrease and the second peak at lower temperatures in those respective quantities to a transverse (quantum) spin fluctuation. It is verified that such anomalies may be produced by interruption by a semiclassical liquidlike state consisting of doubletlike triangular trimmers between a higher-temperature classical spin gaslike state and a lower-temperature quantum spin singlet state. The IAHM may give a general viewpoint for interpreting the experimentally observed thermodynamic properties of spin systems with various triangle-based lattices.