Electron–phonon interaction and superconductivity in the La3 Ni2 B2 N3

Abstract

Based on first-principles pseudopotential plane-wave method within the generalised gradient approximation, we have studied the structural, electronic, vibrational and BCS superconducting properties of (Formula presented.). The calculated electronic properties for (Formula presented.) depict three-dimensional rather than two-dimensional characteristics in spite of the apparent two-dimensionality in its atomic structure. At the zone centre only three (Formula presented.) (La–La optical) and the single (Formula presented.) (Ni–Ni optical) phonon modes couple strongly with electrons. However, a critical assessment of the Eliashberg spectral function throughout the Brillouin zone reveals that all phonon modes except the two highest frequency phonon modes couple considerably with the electrons at the Fermi energy. By integrating the Eliashberg spectral function, the values of the average electron–phonon coupling constant and the logarithmic average frequency are found to be 0.73 and 301.23 K, respectively. Inserting these values into the Allen–Dynes formula with using a reasonable value of (Formula presented.)= 0.10 for the effective Coulomb repulsion parameter, the value of superconducting transition temperature is found to be 11.61 K which compares well with its experimental values of 12–13 K and 11.7 K.