Indexed on: 22 May '12Published on: 22 May '12Published in: Indian Journal of Physics
The role of next–nearest–neighbor (NNN) hopping of the d-electrons in the mixed-valence phenomena has been investigated. Falicov-Kimball model extended by NNN hopping has been considered. Calculations have been made both at zero and at finite temperatures. It has been observed that NNN hopping (i) shifts the d-level energy, (ii) makes the system more disordered, (iii) decreases degeneracy of the ground state and (iv) has important effects on the spin susceptibility. Antiferromagnetic type exchange interaction has also played similar role as NNN hopping in the spin susceptibility χ.