Europhys. Lett.
Volume 63, Number 5, September 2003
Page(s) 743 - 749
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 November 2003
DOI: 10.1209/epl/i2003-00592-1
Europhys. Lett., 63 (5) , pp. 743-749 (2003)

Possible high-temperature superconductivity in hole-doped $\chem{MgB_2C_2}$

A. K. Verma1, P. Modak1, D. M. Gaitonde1, R. S. Rao1, B. K. Godwal1 and L. C. Gupta2

1  High Pressure Physics Division, Bhabha Atomic Research Centre Mumbai 400085, India
2  Tata Institute of Fundamental Research - Homi Bhabha Road Mumbai 400005, India

(Received 1 November 2002; accepted in final form 27 June 2003)

We report first-principles full potential linearised augmented plane wave calculations of the electronic band structure of the compound $\chem{MgB_2C_2}$ and its hole-doped derivatives $\chem{Mg_{0.5}Li_{0.5}B_2C_2}$, $\chem{Mg_{0.5}Na_{0.5}B_2C_2}$, $\chem{Mg_{0.9}Na_{0.1}B_2C_2}$ and $\chem{Mg_{0.5}K_{0.5}B_2C_2}$. The parent compound $\chem{MgB_2C_2}$ is a band insulator, which on hole doping, is predicted to turn metallic with a large density of states at the Fermi energy. Its band dispersion shows a flat band feature close to the Fermi energy, reminiscent of $\chem{MgB_2}$. Based on our estimates of changes in the density of states at the Fermi level, we predict that hole-doped $\chem{MgB_2C_2}$ is a potential candidate for high-temperature superconductivity .

74.25.Jb - Electronic structure.
74.25.Kc - Phonons.
74.70.Ad - Metals; alloys and binary compounds (including A15, $\chem{MgB_2}$, etc.).

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