First-principles investigation of superconductivity in the body-centred tetragonal

Abstract

We have investigated the ground state and electronic properties of in the structure using a generalised gradient approximation of the density functional theory and the ab initio pseudopotential method. We find that the calculated electronic properties of exhibit three-dimensional rather than two-dimensional characteristics in spite of the apparent two dimensionality in its atomic structure. An interesting feature of the phonon dispersion curves is the phonon anomaly in the lowest transverse acoustic branch as well as the longitudinal acoustic branch. We have shown that these phonon anomalies give rise to large electron-phonon interaction, as is evident from the calculated Eliashberg spectral function F(). By integrating this spectral function, the value of average electron-phonon coupling parameter is calculated to be 0.85, from which the superconducting critical temperature is estimated to be 3.74 K, in gratifying accord with its experimental value of 4.0 K.

Keywords:

• Ab initio; density-functional theory; electronic properties; phonons; superconductivity

Acknowledgements

Some of the calculations for this project were carried out using the computing facilities on the Intel Nehalem (i7) cluster (ceres) in the School of Physics, University of Exeter, United Kingdom.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Scientific and Technical Research Council of Turkey (TÜBİTAK) [project number MFAG-114F192].