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Two energy gaps and Fermi-surface "arcs" in NbSe2
S V Borisenko1, A A Kordyuk, V B Zabolotnyy
1Leibniz-Institute for Solid State Research, IFW-Dresden, D-01171, Dresden, Germany.
Physical Review Letters
|June 13, 2009
Summary
Researchers directly observed an energy gap in 2H-NbSe2 caused by charge-density waves (CDW). This CDW-induced gap, similar to cuprate pseudogaps, impacts superconductivity by altering the Fermi surface.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Charge-density waves (CDW) are a common phenomenon in low-dimensional materials.
- Understanding the interplay between CDW, normal state properties, and superconductivity is crucial.
Purpose of the Study:
- To directly observe and characterize the energy gap induced by charge-density waves in 2H-NbSe2.
- To investigate the relationship between the CDW gap and superconductivity.
Main Methods:
- Angle-resolved photoemission spectroscopy (ARPES) was employed to probe the electronic structure.
- ARPES allows for direct observation of energy gaps and Fermi surface modifications.
Main Results:
- Direct observation of an energy gap opening in 2H-NbSe2 due to charge-density waves.
- The gap formation is linked to a nesting mechanism in momentum space.
- The energy gap persists in the normal state (T>T0), breaking the Fermi surface into arcs.
- The gap exhibits nonmonotonic temperature dependence with a minimum at the CDW transition temperature (T0).
Conclusions:
- The observed energy gap is a direct consequence of charge-density wave formation.
- The CDW gap significantly influences superconductivity by excluding nested Fermi surface portions.
- The findings reveal remarkable analogies with the pseudogap phenomenon in cuprates.
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