Extended phonon collapse and the origin of the charge-density-wave in NbSe{sub 2}.

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Phys. Rev. Lett.

DOI:https://doi.org/10.1103/PhysRevLett.107.107403· OSTI ID:1025713

Weber, F; Rosenkranz, S; Castellan, J -P; Osborn, R; Hott, R; Heid, R; Bohnen, K -P; Egami, T; Said, A H; Reznik, D ^[1]

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1. X-Ray Science Division

We report inelastic x-ray scattering measurements of the temperature dependence of phonon dispersion in the prototypical charge-density-wave (CDW) compound 2H-NbSe{sub 2}. Surprisingly, acoustic phonons soften to zero frequency and become overdamped over an extended region around the CDW wave vector. This extended phonon collapse is dramatically different from the sharp cusp in the phonon dispersion expected from Fermi surface nesting. Instead, our experiments, combined with ab initio calculations, show that it is the wave vector dependence of the electron-phonon coupling that drives the CDW formation in 2H-NbSe{sub 2} and determines its periodicity. This mechanism explains the so far enigmatic behavior of CDW in 2H-NbSe{sub 2} and may provide a new approach to other strongly correlated systems where electron-phonon coupling is important.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1025713
• Report Number(s): ANL/MSD/JA-70090
• Journal Information: Phys. Rev. Lett., Journal Name: Phys. Rev. Lett. Journal Issue: 10 ; 2011 Vol. 107; ISSN 0031-9007
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACOUSTICS
CUSPED GEOMETRIES
ELECTRON-PHONON COUPLING
FERMI LEVEL
ORIGIN
PERIODICITY
PHONONS
SCATTERING
TEMPERATURE DEPENDENCE
VECTORS