1998/04/30 by Lev P. Gor`kov, Vladimir Z. Kresin
Physics and Astronomy · #cond-mat.str-el
published as Pis`ma v ZhETF 67(1998)934 · 3.5 pages,no figures
arxiv created 1998/04/30 · arxiv updated 2009/11/30
A tight-band model is employed for the e2g-orbitals in manganites. It is shown that a large intraatomic Hund's coupling, JH and the resulting double-exchange mechanism lead to antiferromagnetic ordering along one of the cubic axis stabilized by the cooperative JT effect which further decreases the band energy of electrons. As a result, LaMnO3 is a band insulator built of 2D ferromagnetic layers. The critical concentration xc≃ 0.16, for onset of ferromagnetic and metallic behavior at low temperatures in La1-xSrxMnO3 and the phase transition are treated in the percolation approach.