  Motivated by the recent indications of ferromagnetism in transition metal
oxide heterostructures, we propose a possible mechanism to generate
ferromagnetism for itinerant t2g systems in two spatial dimensions that does
not rely on the coupling between local moments and conduction electrons. We
particularly emphasize the orbital nature of different bands and show that,
when the Fermi level lies near the bottom of the upper bands, a
non-perturbative interaction effect due to the quasi-one-dimensional nature of
the upper bands may drive a transition to a state in which the upper bands are
ferromagnetically polarized. In the quasi-one-dimensional limit, the full
thermodynamics may be obtained exactly. We discuss the connection between our
mechanism with several itinerant t2g systems that may have ferromagnetic
instabilities.
