Two-dimensional electron gas in δ -doped SrTiO3

It is shown that Shubnikov-de Haas oscillations in SrTiO3 δ -doped with La can be understood as arising from a two-dimensional electron gas of one subband immersed in the space charge layer. Despite the inherent complexity of a subband that is derived from four d -band states near the conduction-band minimum of SrTiO3, the quantum oscillations can be modeled quantitatively by recognizing that the magnetic field (B) induced effective spin splitting and Landau-level splitting are comparable. The oscillations are not strictly periodic in 1/B, which can be understood as caused by a weak dependence of the electron density on the magnetic field in the subband that produces the observed oscillations.