Fractionally delta-doped oxide superlattices for higher carrier   mobilities
  A 2D electron gas system in an oxide heterostructure serves as an important playground for novel phenomena. Here, we show that, by using fractional delta-doping to control the interface's composition in LaxSr1-xTiO3/SrTiO3 artificial oxide superlattices, the filling-controlled 2D insulator-metal transition can be realized. The atomic-scale control of d-electron band filling, which in turn contributes to the tuning of effective mass and density of the charge carriers, is found to be a fascinating route to substantially enhanced carrier mobilities. 
Woo Seok Choi, Suyoun Lee, Valentino R. Cooper, and Ho Nyung Lee
cond-mat.str-el cond-mat.mes-hall cond-mat.mtrl-sci