Role of four-spin exchange in a magnetic mechanism of superconductivity in cuprates

Alexander V. Shnurenko^a, Sergey G. Ovchinnikov^b, Elena I. Shneyder<sup>c

a</sup> Institute of Engineering Physics and Radioelectronics, Siberian Federal University, Krasnoyarsk, Russia
^b L. V. Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, Russia
^c M. F. Reshetnev Siberian State Aerospace University, Krasnoyarsk, Russia

Abstract: Amendments to the exchange interaction can alter the superconducting transition temperature, so on the basis of numerical self-consistent solution of two equations in the framework of the $t$-$J$ model, we investigate the influence of the four spin exchange on the concentration dependence of the transition temperature to the superconducting phase with $d_{x^2-y^2}$ – the type of symmetry of the order.

Keywords: strong electron correlation, Hubbard model, $t$-$J$ model.

UDC: 53.01+538.955+538.915

Received: 18.09.2010
Received in revised form: 25.11.2010
Accepted: 10.12.2010