The insulator to metal transition in LaTiO_3 induced by La substitution via Sr is studied within multi-band exact diagonalization dynamical mean field theory at finite temperatures. It is shown that weak hole doping triggers a large interorbital charge transfer, with simultaneous electron and hole doping of t2g subbands. The transition is first-order and exhibits phase separation between insulator and metal. In the metallic phase, subband compressibilities become very large and have opposite

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... ns. Electron doping gives rise to an interorbital charge flow in the same direction as hole doping. These results can be understood in terms of a strong orbital depolarization.