Thickness-dependent polaron crossover in tellurene.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Polarons (electron-phonon quasiparticles) are key to phenomena like superconductivity.
• Investigating polarons in low-dimensional materials with varying electronic and phonon properties is underexplored.

Purpose of the Study:

• To study polaron formation in tellurene, a low-dimensional material.
• To understand the influence of phonon polarity and electronic structure on polarons.

Main Methods:

• Analysis of A1 phonon frequency and linewidth changes with tellurene thickness.
• Transport measurements (field-effect mobility).
• Theoretical modeling using effective field theory with phonon renormalization.

Main Results:

• Abrupt changes in phonon properties and mobility below 10 nm thickness.
• Evidence of a polaron crossover from large (bulk Te) to small (few-layer tellurene).
• Theoretical model semiquantitatively explains observed phonon hardening and broadening.

Conclusions:

• The quasi-one-dimensional nature of tellurene drives the polaron crossover.
• Reduced dielectric screening and enhanced electron-phonon coupling in few-layer tellurene.
• Polarons significantly influence tellurene's phononic, electronic, and structural characteristics.