| Autor: |
Hänke, T., Sykora, S., Schlegel, R., Baumann, D., Harnagea, L., Wurmehl, S., Daghofer, M., Büchner, B., Brink, J. van den, Hess, C. |
| Rok vydání: |
2011 |
| Předmět: |
|
| Zdroj: |
Phys. Rev. Lett. 108, 127001 (2012) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1103/PhysRevLett.108.127001 |
| Popis: |
A crucial step in revealing the nature of unconventional superconductivity is to investigate the symmetry of the superconducting order parameter. Scanning tunneling spectroscopy has proven a powerful technique to probe this symmetry by measuring the quasiparticle interference (QPI) which sensitively depends on the superconducting pairing mechanism. A particularly well suited material to apply this technique is the stoichiometric superconductor LiFeAs as it features clean, charge neutral cleaved surfaces without surface states and a relatively high Tc~18K. Our data reveal that in LiFeAs the quasiparticle scattering is governed by a van-Hove singularity at the center of the Brillouin zone which is in stark contrast with other pnictide superconductors where nesting is crucial for both scattering and s+- superconductivity. Indeed, within a minimal model and using the most elementary order parameters, calculations of the QPI suggest a dominating role of the hole-like bands for the quasiparticle scattering. Our theoretical findings do not support the elementary singlet pairing symmetries s++, s+-, and d-wave. This brings to mind that the superconducting pairing mechanism in LiFeAs is based on an unusual pairing symmetry such as an elementary p-wave (which provides optimal agreement between the experimental data and QPI simulations) or a more complex order parameter (e.g. s+id-wave symmetry). |
| Databáze: |
arXiv |
| Externí odkaz: |
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