Anomalous transport in high-mobility superconducting SrTiO₃ thin films

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Subtle transport effects in semiconductors necessitate high-quality epitaxial structures with minimal defects.
• Strontium titanate (SrTiO3) is a key material for studying complex electronic phenomena.

Purpose of the Study:

• To achieve high-quality SrTiO3 films using hybrid MBE.
• To investigate the impact of electronic band structure changes and phase transitions on transport properties.
• To elucidate the roles of intraband scattering and antiferrodistortive domain walls.

Main Methods:

• Hybrid molecular beam epitaxy (MBE) for film growth.
• Temperature-dependent transport measurements.
• Phenomenological modeling and scanning superconducting quantum interference device (SQUID) imaging.

Main Results:

• Achieved SrTiO3 films with mobility > 42,000 cm2 V-1 s-1 at 3 × 1017 cm-3 carrier density.
• Observed decreased resistivity and enhanced superconductivity at the second Lifshitz transition, indicating intraband scattering.
• Noted anomalous Hall carrier density linked to the antiferrodistortive (AFD) transition.

Conclusions:

• Hybrid MBE is effective for producing high-quality SrTiO3.
• Intraband scattering and AFD domain walls significantly influence SrTiO3's normal-state and superconducting properties.
• Understanding these factors is crucial for optimizing SrTiO3-based devices.