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Insight into the Charge Density Wave Gap from Contrast Inversion in Topographic STM Images
- Source :
- Physical Review Letters, Vol. 125, No 267603 (2020)
- Publication Year :
- 2020
-
Abstract
- Charge density waves (CDWs) are understood in great details in one dimension, but they remain largely enigmatic in two dimensional systems. In particular, numerous aspects of the associated energy gap and the formation mechanism are not fully understood. Two long standing riddles are the amplitude and position of the CDW gap with respect to the Fermi level ($E_F$) and the frequent absence of CDW contrast inversion (CI) between opposite bias scanning tunneling microscopy (STM) images. Here, we find compelling evidence that these two issues are intimately related. Combining density functional theory and STM to analyse the CDW pattern and modulation amplitude in 1$T$-TiSe$_2$, we find that CI takes place at an unexpected negative sample bias because the CDW gap opens away from $E_F$, deep inside the valence band. This bias becomes increasingly negative as the CDW gap shifts to higher binding energy with electron doping. This study shows the importance of CI in STM images to identify periodic modulations with a CDW and to gain valuable insight into the CDW gap, whose measurement is notoriously controversial.<br />Comment: Main text 8 pages, 4 figures + Supplemental Material 7 pages, 6 figures
- Subjects :
- Charge density waves
Band gap
Binding energy
FOS: Physical sciences
General Physics and Astronomy
ddc:500.2
01 natural sciences
law.invention
symbols.namesake
law
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
0103 physical sciences
010306 general physics
Scanning tunneling microscopy
TiSe2
Physics
Condensed Matter - Materials Science
Charge density wave gap
Condensed Matter - Mesoscale and Nanoscale Physics
Condensed matter physics
Fermi level
Materials Science (cond-mat.mtrl-sci)
Charge density
Amplitude
Electronic properties
symbols
Density functional theory
Scanning tunneling microscope
Charge density wave
Subjects
Details
- ISSN :
- 10797114 and 00319007
- Volume :
- 125
- Issue :
- 26
- Database :
- OpenAIRE
- Journal :
- Physical review letters
- Accession number :
- edsair.doi.dedup.....44a06cb67aaf95b27b043a604a88877c