Polar Discontinuity Doping of the ${\mathrm{LaVO}}_3/{\mathrm{SrTiO}}_3$ Interface

We have investigated the transport properties of ${\mathrm{LaVO}}_3/{\mathrm{SrTiO}}_3$ Mott-insulator–band-insulator heterointerfaces for various configurations. The (001)-oriented $n$-type ${\mathrm{VO}}_2/\mathrm{LaO}/{\mathrm{TiO}}_2$ polar discontinuity is conducting, exhibiting a ${\mathrm{LaVO}}_3$ thickness-dependent metal-insulator transition and low temperature anomalous Hall effect. The (001) $p$-type ${\mathrm{VO}}_2/\mathrm{SrO}/{\mathrm{TiO}}_2$ interface, formed by inserting a single layer of bulk metallic ${\mathrm{SrVO}}_3$ or SrO, drives the interface insulating. The (110) heterointerface is also insulating, indicating interface conduction arising from electronic reconstructions.

Figure 1

Schematic illustrations and growth of two possible configurations of the interface between ${\mathrm{LaVO}}_3$ and ${\mathrm{SrTiO}}_3$ in the (001) orientation. (a) Schematic of the (001) ${\mathrm{VO}}_2/\mathrm{LaO}/{\mathrm{TiO}}_2$ interface, inducing an $n$-type polar discontinuity. (b) RHEED intensity oscillations for the growth of ${\mathrm{LaVO}}_3$ on the ${\mathrm{TiO}}_2$-terminated (001) ${\mathrm{SrTiO}}_3$ substrate. (c) Schematic of the (001) ${\mathrm{VO}}_2/\mathrm{SrO}/{\mathrm{TiO}}_2$ interface, inducing a $p$-type polar discontinuity. (d) RHEED oscillations for the growth of 1 u.c. ${\mathrm{SrVO}}_3$ followed (with a $\sim 25\mathrm{s}$ delay) by ${\mathrm{LaVO}}_3$ on the ${\mathrm{TiO}}_2$-terminated (001) ${\mathrm{SrTiO}}_3$ substrate. Arrows in (a) and (c) denote the chemical interface.

Figure 2

Temperature dependent resistivity $\rho (T)$ of the ${\mathrm{LaVO}}_3/{\mathrm{SrTiO}}_3$ structure for various configurations. Three-dimensional resistivity ${\rho }_{3\mathrm{D}}$ (a) and two-dimensional resistivity ${\rho }_{2\mathrm{D}}$ (b) for a variety of ${\mathrm{LaVO}}_3$ thicknesses with the (001) ${\mathrm{VO}}_2/\mathrm{LaO}/{\mathrm{TiO}}_2$ $n$-type interface. (c) ${\rho }_{2\mathrm{D}}(T)$ for configurations of the (001) ${\mathrm{VO}}_2/\mathrm{SrO}/{\mathrm{TiO}}_2$ $p$-type interface using $({\mathrm{LaVO}}_3{)}_{50\mathrm{u}.\mathrm{c}.}/({\mathrm{SrVO}}_3{)}_{1\mathrm{u}.\mathrm{c}.}/{\mathrm{SrTiO}}_3(001)$ and the nonpolar (110) $({\mathrm{LaVO}}_3{)}_{50\mathrm{u}.\mathrm{c}.}/{\mathrm{SrTiO}}_3$ interface.

Figure 3

${\rho }_{2\mathrm{D}}(T)$ for $({\mathrm{LaVO}}_3{)}_{100\mathrm{u}.\mathrm{c}.}/{\mathrm{SrTiO}}_3(001)$, for variable insertion of 0 to 1 monolayer of SrO, going from the $n$-type to the $p$-type interface.

Figure 4

${\mathrm{LaVO}}_3$ thickness dependence of the transport properties for the (001) ${\mathrm{VO}}_2/\mathrm{LaO}/{\mathrm{TiO}}_2$ $n$-type interface at the measurement temperatures of 280 and 100 K. The thickness dependence of ${\rho }_{2\mathrm{D}}$ (a), carrier density $n$ (b), and mobility $\mu$ (c) are given. Solid and dashed lines are guides to the eye.

Figure 5

Magnetic field and temperature dependence of Hall resistance $R_{xy}(T,H)$. (a) $R_{xy}(T,H)$ of the (001) ${\mathrm{VO}}_2/\mathrm{LaO}/{\mathrm{TiO}}_2$ $n$-type interface for $({\mathrm{LaVO}}_3{)}_{1000}\mathrm{u}.\mathrm{c}./{\mathrm{SrTiO}}_3(100)$. (b) $R_{xy}(H)$ normalized to the 14 T value for different thicknesses of ${\mathrm{LaVO}}_3$ at the measurement temperature of 10 K. The inset shows the original $R_{xy}(H)$ data before normalization.