Investigation of Charge Density Waves and Layer Stacking in Niobium Ditelluride

Author

Gavin J. Smith, University of New Hampshire, DurhamFollow

Date of Award

Spring 2024

Project Type

Senior Honors Thesis

College or School

CEPS

Department

Physics and Astronomy

Program or Major

Physics

Degree Name

Bachelor of Science

First Advisor

Shawna Hollen

Abstract

NbTe₂ is a layered transition metal dichalcogenide which exhibits charge density waves (CDWs) and superconductivity in the bulk. Previous scanning tunneling microscopy and spectroscopy experiments suggested that Fermi-surface nesting and reciprocal lattice reconstruction are important in the formation of CDWs in NbTe₂. These experiments focused on spectroscopy of pristine regions. We will present low temperature scanning tunneling spectroscopy experiments examining the 3x1 CDW in NbTe₂ at 10K. We found a crystalline step and multiple neighboring 60º and 120º CDW domain boundaries. We examined the electronic structure across these domain boundaries and in neighboring domains using scanning tunneling spectroscopy. We observed zig-zag distortions in the dI/dV maps over the domain boundaries for tip bias of 300mV, in contrast to a tip bias of 150mV where we see no electronic distortion. At neighboring mirror-twin 120º boundaries the electronic states differed, while the spectroscopy away from the boundaries stayed consistent. These and future experiments will help elucidate CDW domain formation and interlayer coupling.

Recommended Citation

Smith, Gavin J., "Investigation of Charge Density Waves and Layer Stacking in Niobium Ditelluride" (2024). Honors Theses and Capstones. 812.
https://scholars.unh.edu/honors/812