Phonon anomalies and superconductivity in the Heusler compound YPd2Sn

Abstract

We have studied the structural and electronic properties of YPd2Sn in the Heusler structure using a generalized gradient approximation of the density functional theory and the ab initio pseudopotential method. The electronic results indicate that the density of states at the Fermi level is primarily derived from Pd d states, which hybridize with Y d and Sn p states. Using our structural and electronic results, phonons and electron-phonon interactions have been studied by employing a linear response approach based on the density functional theory. Phonon anomalies have been observed for transverse acoustic branches along the [110] direction. This anomalous dispersion is merely a consequence of the strong coupling. By integrating the Eliashberg spectral function, the average electron-phonon coupling parameter is found to be λ = 0.99. Using this value, the superconducting critical temperature is calculated to be 4.12 K, in good accordance with the recent experimental value of 4.7 K.