Role of orbital degeneracy in double-exchange systems - art. no. 214419

We investigate the role of orbital degeneracy in the double-exchange model. In the J(H)--> infinity limit, an effective generalized "Hubbard" model in corporating orbital pseudospin degrees of freedom is derived. The model pos sesses an exact solution in one and in infinite dimensions. In one-dimensio n, the metallic phase off ''half-filling" is a Luttinger liquid with pseudo spin-charge separation. Using the d=infinity solution for our effective mod el, we show how many experimental observations for the well-doped (x simila r or equal to0.3) three-dimensional manganites La1-xSrxMnO3 can be qualitat ively explained by invoking the role of orbital degeneracy in the double ex change model.