The influence of the SrTiO$_{\mathrm{3}}$ capping layer to the two-dimensional electron liquid at the interface of LaAlO$_{\mathrm{3}}$/SrTiO$_{\mathrm{3}}$.

The discovery of 2-dimensional electron liquid (2DEL) at the interface of LaAlO$_{\mathrm{3}}$/SrTiO$_{\mathrm{3}}$ (LAO/STO) has attracted enormous interests due to its fascinating behaviours, such as magnetism, superconductivity, and unexpectedly coexistence of the two. Inspired by earlier works, a STO capping layer on LAO/STO can largely affect the electronic reconstruction at the interface, possibly giving rise to a parallel 2D electron-hole bilayer. In this work, we used oxide molecular beam epitaxy technique to grow high-quality films of STO(x nm)/LAO(y nm)/STO(001)(substrate) heterostructures with different x and y values. Influences of the capping layer on 2DEL and related magnetotransport properties will be systematically studied and discussed.