Conducting Domain Walls in van der Waals Ferroelectric NbOI₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Layered transition metal oxide dihalides, such as niobium oxyiodide (NbOI2), are ferroelectric semiconductors with in-plane polarization.
• These materials exhibit 180° domain walls, with both neutral and charged types present in pristine 2D flakes.

Purpose of the Study:

• To investigate the electronic properties of domain walls in NbOI2.
• To understand how charged domain walls influence the modification of ferroelectric domain structures.

Main Methods:

• Scanning probe microscopy techniques were employed.
• Piezoresponse force microscopy (PFM) was used for domain imaging.
• Conductive atomic force microscopy (C-AFM) was used for electrical measurements.

Main Results:

• Charged domain walls in NbOI2 exhibit a conductive nature.
• The conductivity of charged domain walls was confirmed through C-AFM measurements.
• Modification of as-grown domain structures by a biased probing tip is possible but challenging.

Conclusions:

• The high conductivity of charged domain walls in NbOI2 significantly hampers their manipulation.
• Understanding these electronic properties is crucial for potential applications in ferroelectric devices.