Spin frustration, charge ordering, and enhanced antiferromagnetism in TMTTF2SbF6

Abstract: We theoretically investigate the effects of charge order and spin frustration on the spin ordering in TMTTF salts. Using first-principles band calculations, we find that a diagonal inter-chain transfer integral t q1, which causes spin frustration between the inter-chain dimers in the dimer-Mott insulating state, strongly depends on the choice of anion. Within the numerical Lanczos exact diagonalization method, we show that the ferroelectric charge order changes the role of t q1 from the spin frustration to the enhancement of the two-dimensionality in spin sector. The results indicate that t q1 assists the cooperative behavior between charge order and antiferromagnetic state observed in TMTTF2SbF6. [Copyright &y& Elsevier]