Domain wall conductivity in semiconducting hexagonal ferroelectric TbMnO3 thin films.

Area of Science:

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

Background:

• Enhanced conductivity at ferroelectric domain boundaries is a known phenomenon in materials like BiFeO3 and Pb(Zr,Ti)O3.
• The precise mechanisms driving domain wall conductivity, especially in hexagonal rare-earth manganites, remain under investigation.
• Previous studies often focused on charged domain walls as the primary source of enhanced conductance.

Purpose of the Study:

• To investigate the conductivity of electrically-neutral domain walls in semiconducting hexagonal ferroelectric TbMnO3 thin films.
• To elucidate the underlying conduction mechanism responsible for the observed domain wall conductivity.
• To determine if domain wall conductivity in this material is limited to charged domain walls.

Main Methods:

• Utilized conductive atomic force microscopy (c-AFM) to probe the local electronic transport properties.
• Fabricated and characterized TbMnO3 thin films with c-axis constrained structure and polarization.
• Analyzed the conductance data to identify the dominant conduction mechanism.

Main Results:

• Observed significantly enhanced conductance at electrically-neutral domain walls in TbMnO3 thin films.
• Demonstrated that domain wall conductivity is not exclusively linked to charged domain walls in these materials.
• Identified a single, consistent conduction mechanism: back-to-back Schottky diodes influenced by defect segregation.

Conclusions:

• Domain wall conductivity in hexagonal rare-earth manganites like TbMnO3 can occur at electrically-neutral walls.
• The observed conductivity is governed by defect-segregated Schottky barriers, providing a unified mechanism.
• This finding expands the understanding of electronic transport phenomena in ferroelectric domain walls.