Atomic-scale strain manipulation of a charge density wave

Shang Gao; Felix Flicker; Raman Sankar; He Zhao; Zheng Ren; Bryan Rachmilowitz; Sidhika Balachandar; Fangcheng Chou; Kenneth S Burch; Ziqiang Wang; Jasper van Wezel; Ilija Zeljkovic

doi:10.1073/pnas.1718931115

Atomic-scale strain manipulation of a charge density wave

Proc Natl Acad Sci U S A. 2018 Jul 3;115(27):6986-6990. doi: 10.1073/pnas.1718931115. Epub 2018 Jun 18.

Authors

Shang Gao¹, Felix Flicker^{2

3}, Raman Sankar^{4

5}, He Zhao¹, Zheng Ren¹, Bryan Rachmilowitz¹, Sidhika Balachandar¹, Fangcheng Chou⁴, Kenneth S Burch¹, Ziqiang Wang¹, Jasper van Wezel⁶, Ilija Zeljkovic⁷

Affiliations

¹ Department of Physics, Boston College, Chestnut Hill, MA 02467.
² Department of Physics, University of California, Berkeley, CA 94720.
³ Clarendon Laboratory, Department of Physics, The Rudolph Peierls Centre for Theoretical Physics, University of Oxford, OX1 3PU Oxford, United Kingdom.
⁴ Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan.
⁵ Institute of Physics, Academia Sinica, Nankang, 11529 Taipei, Taiwan.
⁶ Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, 1090 GL Amsterdam, The Netherlands.
⁷ Department of Physics, Boston College, Chestnut Hill, MA 02467; ilija.zeljkovic@bc.edu.

Abstract

A charge density wave (CDW) is one of the fundamental instabilities of the Fermi surface occurring in a wide range of quantum materials. In dimensions higher than one, where Fermi surface nesting can play only a limited role, the selection of the particular wavevector and geometry of an emerging CDW should in principle be susceptible to controllable manipulation. In this work, we implement a simple method for straining materials compatible with low-temperature scanning tunneling microscopy/spectroscopy (STM/S), and use it to strain-engineer CDWs in 2H-NbSe₂ Our STM/S measurements, combined with theory, reveal how small strain-induced changes in the electronic band structure and phonon dispersion lead to dramatic changes in the CDW ordering wavevector and geometry. Our work unveils the microscopic mechanism of a CDW formation in this system, and can serve as a general tool compatible with a range of spectroscopic techniques to engineer electronic states in any material where local strain or lattice symmetry breaking plays a role.

Keywords: NbSe2; charge density waves; scanning tunneling microscopy; strain.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't