Nanoscale Conductive Sheets in Ferroelectric BaTiO3: Large Hall Electron Mobilities at Head-to-Head Domain Walls

Strongly charged head-to-head domain walls that are purposely engineered along the [110] crystallographic orientation into ferroelectric BaTiO3 single crystals have been proposed as intrinsically nanoscaled two-dimensional electron gases (2DEGs) because of their significant conductivity. Here, we quantify these 2DEG properties through dedicated Hall transport measurements in van der Pauw 4-point geometry, finding the electron mobility to reach around 400 cm2 (V s)^{−1}, while the two-dimensional charge density amounts to 7 × 103 cm^{–2}. We underline the necessity to take into account the thermal and geometrical misalignment offset voltages by evaluating the Hall resistance under magnetic field sweeps; otherwise, errors of several hundred percent in the derived transport parameters can occur.