Volume 87, Number 1, July 2009
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||24 July 2009|
Possible strong electron-lattice interaction and giant magneto-elastic effects in Fe-pnictides
Goethe-University Frankfurt, Theoretical Physics - 60054 Frankfurt/Main, Germany, EU
2 Goethe-University Frankfurt, Institute of Physics - 60054 Frankfurt/Main, Germany, EU
Corresponding author: firstname.lastname@example.org
Accepted: 25 June 2009
The possibility for an appreciable many-body contribution to the electron-phonon interaction (EPI) in Fe-pnictides is discussed in the model where EPI is due to the electronic polarization of As-ions. The polarization induced EPIpol potential Vep is large for vibrations of the As-ions and depends strongly on the As-Fe distance d, i.e. Vep ~ d-4. The EPIpol coupling is much larger than the one obtained in the LDA band structure calculations, with (~16 eV/Å) ( < 1 eV/Å) and the bare pairing EPIpol coupling constant ~ 1. It contributes significantly to the intra-band s-wave pairing and an appreciable positive As-isotope effect in the superconducting critical temperature is expected. In the Fe-breathing mode the linear (in the Fe-displacements) EPIpol coupling vanishes, while the non-linear (quadratic) one is very strong. The part of the EPIpol coupling, which is due to the “potential" energy (the Hubbard U) changes, is responsible for the giant magneto-elastic effects in MFe2As2, M = Ca, Sr, Ba since it gives much larger contribution to the magnetic pressure than the band structure effects do. This mechanism is contrary to the LDA prediction where the magneto-elastic effects are due to the “kinetic" energy effects, i.e. the changes in the density of states by the magneto-elastic effects. The proposed is expected to be operative (and strong) in other Fe-based superconductors with electronically polarizable ions such as Se, Te, S etc., and in high-temperature superconductors due to the polarizability of the O2--ions.
PACS: 74.25.Jb – Electronic structure / 74.25.Kc – Phonons / 74.70.Dd – Ternary, quaternary, and multinary compounds (including Chevrel phases, borocarbides, etc.)
© EPLA, 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.