Abstract
We report seeing a saddle point in the energy band, known as a van Hove singularity. We measure an exact position of the singularity in both YBa2Cu4O8(Y124) and YBa2Cu3O6.9(Y123). In Y123 the van Hove singularity is at binding energy of less then 10 meV, closer ot EF, than in Y124, which has a singularity at 19 meV. The singularity has and extended character along the Γ-Y direction. Another clearly resolved band exhibits a saddle point singularity at binding energy of 115 meV. Similar singularities are observed in the vicinity of the X point, extended along the Γ-X direction. In order to study these features the energy resolution of the system was improved to better than 10 me V.
| Original language | English |
|---|---|
| Pages (from-to) | 1193-1198 |
| Number of pages | 6 |
| Journal | Journal of Physics and Chemistry of Solids |
| Volume | 54 |
| Issue number | 10 |
| DOIs | |
| State | Published - Oct 1993 |
| Externally published | Yes |
Keywords
- ARPES
- Fermi surface
- high T superconductors
- photoemission
- van Hove singularities