(110)-based two-dimensional electron gases

The difference in superconducting critical temperature (T_c) between bidimensional electron gases (2DEGs) based on KTaO₃ with different crystalline orientation continues to puzzle the community. Indeed, the record T_c for KTaO₃ (111)- and KTaO₃ (110)- 2DEGs are around 2.2 K and 1 K respectively, whereas KTaO₃ (001) 2DEGs do not show superconductivity at interfaces. Meanwhile, SrTiO₃ 2DEGs do not exhibit such variability.

As the intermediate system, sharing one high symmetry direction with each other crystalline orientation, (110)-based systems could serve as a gateway for the understanding of the role of interface symmetry in the pairing mechanism. Here, we present ARPES- and transport-based characterisation of KTaO₃ (110) 2DEGs. We observe the elliptical and anisotropic Fermi surface and detail the spin texture. Field-effect magnetotransport experiments with microdevices further reveal anisotropy, with non-reciprocal response, and in the superconducting transition.