Shubnikov-de Haas oscillation of KTaO$_{\mathrm{3}}$ based electron gases

Two-dimensional electron gases (2DEGs) at transition metal oxide (TMO) surfaces and interfaces have attracted much attention due to their exotic properties such as superconductivity, and ferromagnetism. Recently, 5$d$ TMOs are hotly investigated due to their strong spin-orbit coupling (SOC), an indispensable element for topolotical insulating states. Among them, KTaO$_{\mathrm{3}}$ not only hosts 2DEGs but also involves strong SOC. We have created KTaO$_{\mathrm{3}}$ based electron gases, with low temperature mobility as large as 8000cm$^{\mathrm{2}}$V$^{\mathrm{-1}}$s$^{\mathrm{-1}}$. Shubnikov de Haas oscillations in magnetoresistance have been observed at 1.8 K for field applied along various directions. Contributions from $d_{\mathrm{xy}}$ and $d_{\mathrm{xz/yz}}$ bands are both seen. These oscillation curves exhibit a field direction dependence with 4-fold symmetry, revealing the cubic symmetry of Fermi surface of KTaO$_{\mathrm{3}}$ based electon gases. Moreover, the intercept of oscillation indices is close to 0.5, a typical value for systems that involve strong SOC. Our results provide unique insights into the electronic structures of KTaO$_{\mathrm{3}}$ based electron gases via magnetotransport measurements.