Mapping polarization induced surface band bending on the Rashba semiconductor BiTeI

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spintronics

Background:

• Semiconductor surfaces with strong spin-orbit coupling are crucial for spintronic devices.
• The Rashba effect leads to spin splitting in electron bands, important for spintronics.
• Bismuth telluroiodide (BiTeI) exhibits significant Rashba-type spin splitting in both valence and conduction bands.

Purpose of the Study:

• To experimentally identify the two polar terminations of BiTeI surfaces in real space.
• To investigate the electronic structure at the lateral boundary between these terminations.
• To confirm the existence of a p-n junction-like discontinuity.

Main Methods:

• Multi-technique experimental approach for surface characterization.
• Spatially resolved tunneling spectroscopy.
• Analysis of electronic band structure and surface band bending.

Main Results:

• First real-space microscopic identification of the two distinct polar terminations of BiTeI.
• Experimental confirmation of a p-n junction-like electronic structure discontinuity at the lateral boundary between terminations.
• Demonstration of electronically accessible Rashba spin-split bands through surface band bending.

Conclusions:

• The distinct surface terminations and their associated electronic properties in BiTeI have been experimentally verified.
• These findings represent a significant step towards utilizing BiTeI in novel spintronic device concepts.
• The ability to tune Rashba spin-split bands via surface engineering is key for future spintronic applications.