Magnetism and superconductivity inC15compounds from self-consistent band calculations

Abstract

All-atom---all-electron self-consistent semirelativistic linear muffin-tin orbital energy-band studies are reported for Ti${\mathrm{Be}}_{2}$, Zr${\mathrm{Zn}}_{2}$ (at ambient and high pressures), the high-${T}_{c}$ superconductor Zr${\mathrm{V}}_{2}$, and the ultralow-${T}_{c}$ superconductor Y${\mathrm{Al}}_{2}$. Total and partial (by atom type and $l$ values) density of states, Stoner-like parameters, electron-phonon coupling parameter $\ensuremath{\lambda}$ and superconducting transition temperatures ${T}_{c}$ (determined within the rigid muffin-tin approximation and McMillan's strong coupling theory with and without paramagnon contributions), and their behavior under applied pressure are used to discuss the origin of their observed magnetism and/or superconductivity. From an analysis of the results, we suggest possible high-${T}_{c}$ superconductivity at high pressure for Zr${\mathrm{Zn}}_{2}$, and its unlikely occurrence for Ti${\mathrm{Be}}_{2}$ unless dominant soft phonon modes exist.