Exact diagonalization for a 16-site spin-1/2 pyrochlore cluster

Abstract

We find exact solutions to the Hamiltonian of a 16-site spin-1/2 pyrochlore cluster with nearest neighbour exchange interactions. The methods of group theory (symmetry) are used to completely block-diagonalize the Hamiltonian, yielding precise details about symmetry of the eigenstates, in particular those components which are spin ice states, in order to evaluate the spin ice density at finite temperature. At low enough temperatures, a ‘perturbed’ spin ice phase, where the ‘2-in-2-out’ ice rule is largely obeyed, is clearly outlined within the four parameter space of the general model of exchange interactions. The quantum spin ice phase is expected to exist within these boundaries.