Physical properties and electronic structure of La3Co and La3Ni intermetallic superconductors

Abstract

La 3 Co and La 3 Ni are reported superconductors with transition temperatures of 4.5 and 6 K, respectively. Here, we reinvestigate the physical properties of these two intermetallic compounds with magnetic susceptibility χ, specific heat C p and electrical resistivity ρ down to 1.9 K. Although bulk superconductivity is confirmed in La 3 Co, as observed previously, only trace superconductivity is found in La 3 Ni, indicating that the superconductivity in La 3 Ni originates from an impurity phase. Superconducting state parameters for La 3 Co, including lower and upper critical fields and the superconducting gap, are estimated. Results of the theoretical calculations of the electronic structure for both materials are also presented, and comparison of the Fermi level location in La 3 Co versus La 3 Ni explains its larger superconducting T c . A major discrepancy between band structure calculations and the experimentally measured Sommerfeld coefficient is found. The measured electronic density of states is about 2.5 times larger than the theoretical value for La 3 Co. This effect cannot be explained by the electron-phonon interaction alone. This renormalization of g, as well as an ~T 2 behavior of the resistivity, suggests the presence of spin fluctuations in both systems.

Iridium5d-electron driven superconductivity inThIr3

“…To try to quantify this effect, we may follow the route proposed for many d-band superconductors, like Vanadium and its alloys [34][35][36][37][38], Mo 3 Sb 7 [39], La 3 Co [40] or Y 3 Rh [41]. Assuming that the electronic correlations take mostly the form of spin fluctuations (electron-paramagnon interactions), characterized by the coupling constant λ sf , one can compute the superconducting critical temperature from the modified McMillan's formula [39,42]:…”

Electron-phonon coupling in La3In under pressure

“…In 2014 Ram and Kanchana [5] compared Superconducting properties like transition temperature and Fermi surface topology of La 3 In to La 3 InO & La 3 InN compounds to study the effect of oxygen & nitrogen doping. Zhao et al [6] had earlier investigated experimentally the same two compounds La 3 InO & La 3 InN and concluded that while La 3 InO showed superconducting behavior at 10 K, La 3 InN showed no superconducting behavior above 2 K. Strychalska et al [7] in 2016 experimentally synthesized and studied the magnetic susceptibility, specific heat and electrical resistivity of La 3 Co & La 3 Ni and compared the electronic structure properties of both these compounds leading to the conclusion that La 3 Ni has lower T c than La 3 Co. In 2022 Hoffmann et al [8] studied conventional superconductivity in 397 antiperovskites materials among them InBLa 3 , InCLa 3 , InNLa 3 , InOLa 3 using machine learning models and concluded that λ is directly proportional to DOS at the Fermi surface & inversely proportional to the mass of Y-atom (XYZ 3 ).…”