title: Role of the spin magnitude of the magnetic ion in determining the frustration and low-temperature properties of kagome lattices.
abstract: In view of the variety of low-temperature magnetic properties reported recently for kagome lattices with transition-metal ions in different oxidation states, we have investigated the low-energy spectrum and low-temperature thermodynamic properties of antiferromagnetic kagome lattices with varying magnitudes of site spins, employing quantum many-body Heisenberg models. The ground state and the low-lying excitation spectrum are found to depend strongly on the nature of the spin magnitude of the magnetic ions. The system remains highly frustrated if spins are half-odd-integer in magnitude, while the frustration is very weak or almost absent for integer spins or mixed-spin systems. In fact, for a mixed-spin kagome system with a certain magnitude, the whole system behaves as a classical magnet with a ferrimagnetic ground state without any frustration. These theoretical findings are consistent with a few experimental observations recently reported in the literature and would be of value in designing new kagome systems with unusual and interesting low-temperature magnetic properties.
authors.affiliation: Theoretical Sciences Unit and Chemistry and Physics of Materials Unit, Jawharlal Nehru Center for Advanced Scientific Research, Jakkur Campus, Bangalore 560 064, India. pati@jncasr.ac.in
authors.forename: Swapan K
authors.initials: SK
authors.lastname: Pati
authors.forename: C N R
authors.initials: CN
authors.lastname: Rao