the lower and upper Rashba-Dresselhaus bands reaching VHS separately, the shifted VHSs do not have spin degeneracy. While it has been long recognized that the logarithmic VHS at $\mathrm{X}$ enhances the superconducting instability in the spin-singlet channel [-@Schulz1987; -@Dzyaloshinskii1987; -@Furukawa1998; -@Gonzalez2008; -@Nandkishore2012], it was recently shown [-@Meng2015; -@Yao2015; -@Cheng2015] that the logarithmic VHS away from $\mathrm{X}$ enhances the instability to the spin-triplet $p$-wave superconductivity. The physics at $\mathrm{X}$ should be experimentally accessible, as the VHS at $\mathrm{X}$ is not too far from the band bottom of the $d_{xz/yz}$ in energy ($\approx 0.23$ eV), and we will show in the next section how our heterostructure can be chemically doped all the way to the VHS at $\mathrm{X}$. **Discussions**

![\[fig:tao2bho\]Electronic structure of a TaO$_2$ layer on BaO-terminated BaHfO$_3$ (001) from first-principles calculations. (a) Band structure along high-symmetry points in BZ. The dotted horizontal line denotes the energy level of the VHS in absence of the Rashba-Dresselhaus splitting, $E_{vH}$, with the Fermi level set to 0. (b) AM texture at $E_{vH}$ with constant energy lines. The red and blue arrows correspond to the orbital and spin AM, respectively. ](fig5.pdf){width="40.00000%"}

To actually realize the 2DEG in the TaO$_2$ layer, electron doping is needed because 