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Magnon-mediated pairing and isotope effect in iron-based superconductors
Jiansheng Wu1, Philip Phillips
1Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, USA.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|February 23, 2011
Summary
In iron-based superconductors, interband scattering drives sign-reversing superconductivity, even with repulsive interactions. This model explains the coexistence of superconductivity and magnetism, consistent with a non-phononic isotope effect.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Iron-based superconductors exhibit complex electronic properties, including coexistence of superconductivity and magnetic order.
- Understanding the mechanisms behind multiband superconductivity is crucial for novel material design.
Purpose of the Study:
- To derive a general conclusion for multiband superconductivity in iron-based systems.
- To explain the sign-reversing superconductivity and the coexistence of superconductivity and magnetic order.
- To reconcile the large isotope effect with a non-phononic superconducting mechanism.
Main Methods:
- A minimal model incorporating itinerant electrons and local moments.
- Application of the Adler theorem to analyze scattering processes.
- Modeling interband interactions as an internal Josephson link.
Main Results:
- Interband scattering dominates intraband scattering in multiband superconductors at the long wavelength limit.
- This dominance leads to sign-reversing superconductivity, irrespective of interaction repulsion.
- The model successfully explains the coexistence of superconductivity and magnetic order in iron-pnictides.
- A non-phononic mechanism is proposed for the isotope effect, linked to lattice changes and zero-point motion.
Conclusions:
- Interband scattering, mediated by magnons, is a key mechanism for superconductivity in iron-based materials.
- The proposed model provides a unified explanation for observed phenomena, including sign-reversal and magnetic order coexistence.
- The large isotope effect can be explained by non-phononic effects influencing lattice parameters and atomic motion.
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