Abstract
The magnetic properties of the molecular cluster are due to the four ions that have spins and the eight ions with spins These spins are coupled by an exchange mechanism. We determine the four exchange couplings assuming a Heisenberg-type interaction between the ions. We use exact diagonalization of the spin Hamiltonian by a Lánczos algorithm and we adjust the couplings to reproduce the magnetization curve of We also impose the constraint of reproducing a gap of 35 K between an ground state and a first excited state with We predict that there is an excited level with at 37 K above the ground state, only slightly above the excited state that lies at 35 K and the next excited state is an multiplet at 67 K above the ground state.
- Received 10 April 2002
DOI:https://doi.org/10.1103/PhysRevB.66.054409
©2002 American Physical Society