draft Orbital correlations in monolayer manganites — From spin t – J model to orbital t – J model ( a )

On the example of monolayer manganites we show that the theoretical ideas developed long ago along the derivation of the spin t–J model from the Hubbard model are nowadays very helpful in strongly correlated oxides with partly filled degenerate orbitals. We analyze a realistic orbital t–J model for eg electrons in La1−xSr1+xMnO4 monolayer manganites, and discuss the evolution of spin and orbital correlations under increasing doping by performing exact diagonalization of finite clusters, with electronic kinetic energy determined self-consistently at finite temperature by classical Monte Carlo for t2g spins. Several experimental results are reproduced. Spin t–J model. – A new perspective to treat strongly correlated electrons was opened by the derivation of the spin t–J model three decades ago [1]. We argue that this derivation opened new routes to understand the complex magnetic and superconducting instabilities in the Hubbard model, and proved to be a very useful paradigm in strongly correlated electron systems. At that time it was already realized that the Hubbard model,