Theoretical study on the electronic states in hollandite vanadate K2V8O16 Original Research Article

We consider charge and spin properties of the t2gt2g orbital system of one-dimensional zigzag chains of hollandite vanadate K2V8O16. We first calculate the relative stability of charge-ordering patterns to determine the most stable one that is consistent with the observed supercell structure. We then develop the strong-coupling perturbation theory to derive the effective spin–orbit Hamiltonian where we start from the triply degenerate t2gt2g orbitals in the VO6 octahedral structure. We apply an exact-diagonalization technique on small clusters of this Hamiltonian to obtain the orbital-ordering pattern in the ground state. Based on detailed analyses of the calculated spin and orbital structures, we discuss electronic and magnetic properties of K2V8O16.