Preparation and performance analysis of SrHfO3/KTaO3 heterojunction films

Two-dimensional electron gases (2DEGs) at oxide interfaces provide a versatile platform for exploring emergent electronic states arising from strong spin–orbit coupling, interfacial reconstruction, and broken inversion symmetry. Here, we report the realization of a multifunctional 2DEG at a SrHfO 3 /KTaO 3 (SHO/KTO) heterojunction film fabricated by pulsed laser deposition. The structural and spectroscopic characterizations confirm the formation of a well-crystallized SHO/KTO heterojunction films with a well-defined interface. By systematically varying the growth temperature and SHO deposition time, we demonstrate effective control over the interfacial electronic properties. In particular, increasing the SHO deposition time from 2 to 5 min induces an insulator-to-metal transition, with a Hall mobility reaching 99.5 cm 2  V −1  s −1 at 6 K. At low temperatures (T ≤ 10 K), the interface exhibits pronounced weak anti-localization, revealing strong spin–orbit coupling. Maekawa–Fukuyama analysis yields a Rashba spin-splitting energy of 16.61 meV at 2 K, indicating substantial Rashba-type spin–orbit interaction at the SHO/KTO interface. The heterostructures further display wavelength-dependent positive photoresponse and persistent photoconductivity, with a biexponential relaxation behavior indicative of multiple carrier relaxation/trapping channels. Remarkably, an electrically switchable ferroelectric-like polarization state is also observed at the interface, with its magnitude strongly dependent on SHO thickness. These results demonstrate the coexistence of metallic 2DEG conduction, strong Rashba spin–orbit coupling, persistent photoresponse, and ferroelectric-like polarization in a single 5d transition-metal-oxide heterostructure. The SHO/KTO interface therefore provides a promising platform for investigating coupled spin–charge–polarization phenomena and for developing multifunctional oxide electronic and spintronic devices.