Electron-Phonon Interaction in Ternary Rare-Earth Copper Antimonides LaCuSb2 and La(Cu0.8Ag0.2)Sb2 probed by Yanson Point-Contact Spectroscopy

TL;DR

This study investigates the electron-phonon interaction in LaCuSb2 and La(Cu0.8Ag0.2)Sb2 using Yanson point-contact spectroscopy, revealing phonon features, estimating the Debye energy, and observing localized superconductivity.

Contribution

It provides the first detailed analysis of EPI in these compounds and reports the observation of superconductivity at the point contact level.

Findings

Pronounced broad maximum in spectra due to EPI

Estimated Debye energy of about 40 meV

Superconducting phase observed at point contacts with T_c around 6 K

Abstract

Investigation of the electron-phonon interaction (EPI) in LaCuSb2 and La(Cu0.8Ag0.2)Sb2 compounds by Yanson point-contact spectroscopy (PCS) has been carried out. Point-contact spectra display a pronounced broad maximum in the range of 10{\div}20 mV caused by EPI. Variation of the position of this maximum is likely connected with anisotropic phonon spectrum in these layered compounds. The absence of phonon features after the main maximum allows the assessment of the Debye energy of about 40 meV. The EPI constant for the LaCuSb2 compound was estimated to be {\lambda}=0.2+/-0.03. A zero-bias minimum in differential resistance for the latter compound is observed for some point contacts, which vanishes at about 6 K, pointing to the formation of superconducting phase under point contact, while superconducting critical temperature of the bulk sample is only 1K.