Pressure Effects and Large Polarons in Layered MgB_2 Superconductor
Abstract
We consider the dependence of the MgB_2 superconducting critical temperature on the pressure. Our model exploits the influence of the large polarons on the band structure of the layered MgB_2 superconductor. Namely, the hole Pekar-Froehlich polarons form quasi two-dimensional potential wells in the boron plane which shift the positions of the sigma- and pi-bands. This energy shift depends on the pressure and the Cooper pairing of the correlated sigma-electrons happens inside polaron wells. The results obtained are as follows: dT_c/dp = -\alpha (5.2 \pm 0.9) K/GPa or dT_c/dp = -\alpha (6.9\pm 1.1) K/GPa for a different choice of the Grueneisen parameter. Being compared with known experimental data they give us a resonable interval for the value of the Froehlich electron-phonon coupling constant: \alpha = 0.15 - 0.45.
Keywords
Cite
@article{arxiv.cond-mat/0206300,
title = {Pressure Effects and Large Polarons in Layered MgB_2 Superconductor},
author = {V. A. Ivanov and M. A. Smondyrev and J. T. Devreese},
journal= {arXiv preprint arXiv:cond-mat/0206300},
year = {2009}
}
Comments
6 pages, 1 fig, LaTeX, subm. to Phys. Rev. B