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J. Miranda Mena1, T. Mertelj 1,2, V.V. Kabanov1 and D. Mihailovic1,2 1 Josef Stefan Institute, Jamova 39, SI 1001 Ljubljana, Slovenia 2 Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI 1001, Ljubljana, Slovenia Key words: Jahn-Teller, electron-phonon pairing, stripes, cuprates, conductivity, pseudogap. Recently the mechanism for an intersite pairing was proposed for cuprates [1]. It was shown that two fold degenerated level is coupled to local lattice modes due to finite wavevector Jahn-Teller (JT) coupling. The mechanism was based on the following experimental facts: 1) an incommensurate extra phonon mode observed by inelastic neutron scattering (INS) [2], 2) local distortions measured by EXAFS [3], 3) the interpretation of a Jahn-Teller distortion in the three spin magnetic polaron, measured by electron paramagnetic resonance (EPS) [4]. After elimination of vibrational degrees of freedom the model was reduced to the classical lattice model of polarons interacting via the deformation field and direct Coulomb repulsion. Monte Carlo simulations in a wide range of doping and temperature revealed formations of single pairs, clusters and stripes of different sizes [5,6]. Formation of pairs and clusters is accompanied by a suppression of density of states (DOS) at the Fermi level [7]. In this report, we focus in the charge transport properties that can be deduced from the above model. We present patterns created for selected dopings and their single particle DOS and biparticle DOS at different temperatures. We argue that single particle and pair conductivity may differ. For a better analysis on this issue, we compute the contribution to the electrical conductivity arising from single particle using a variable range hopping model. The general trend is that conductivity has a crossover from 1/T temperature behavior at high temperature to a strong reduction of the conductivity at low temperatures. Finally, the gap magnitude in the calculated DOS and the average pair energy, are discussed in relation to the pseudogap region in cuprates. [1] Mihailovic D., Kabanov V. V., Phys. rev., B, Condens. matter mater. phys., vol. 63, pgs 054505-1 (2001) [2] R. J. McQeeney, Y. Petrov, T. Egami, M. Yethiraj, G. Shirane,and Y. Endoh, Phys. Rev. Lett. 82, 628 (1999). [3] A. Bianconi et al., Phys. Rev. Lett. 76, 3412 (1996); N. L. Saini et al., Phys. Rev. B 55, 12 759 (1997). [4] B. I. Kochelaev et al., Phys. Rev. Lett. 79, 4274 (1997). [5]Mertelj T., Kabanov V. V., Mihailovic D., Phys. rev. lett., vol. 94, pgs. 147003-4 (2005) [6] Mertelj T., Kabanov V. V., Miranda Mena J., Mihailovic D., Physical Review B 76, 054523 (2007) [7] Miranda Mena J., Mertelj T., Kabanov V. V., Mihailovic D., J Supercond Nov Magn (2007) 20: 587%G–%@590 DOI 10.1007/s10948-007-0262-3. |
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