The Spin-SAF transition in NaV2O5 induced by spin-pseudospin coupling

TL;DR

This paper investigates the microscopic interactions in NaV2O5, revealing a significant spin-pseudospin coupling that influences charge ordering and spin dimerization, with implications for its phase transitions.

Contribution

It provides the first microscopic estimates of spin-spin and spin-pseudospin interactions in NaV2O5 using exact diagonalization of the Hubbard model.

Findings

Identification of a substantial interladder spin-pseudospin interaction

Evidence for the absence of a soft antiferroelectric mode

Implications for charge ordering and spin dimerization in NaV2O5

Abstract

We present microscopic estimates for the spin-spin and spin-speudospin interactions of the quarter-filled ladder compound NaV2O5, obtained by exactly diagonalizing appropriate clusters of the underlying generalized Hubbard Hamiltonian. We present evidence for a substantial interladder spin-pseudospin interaction term which would allow simultaneously for the superantiferroelectric (SAF) charge (pseudospin) ordering and spin dimerization. We discuss the values of the coupling constants appropriate for NaV2O5 and deduce the absence of a soft antiferroelectric mode.