Evidence for strong electron-phonon coupling in MgCNi_3

Abstract

The title compound is investigated by specific heat measurements in the normal and superconducting state supplemented by upper critical field transport, susceptibility and magnetization measurements. From a detailed analysis including also full potential electronic structure calculations for the Fermi surface sheets, Fermi velocities and partial densities of states the presence of both strong electron-phonon interactions and considerable pair-breaking has been revealed. The specific heat and the upper critical field data can be described to first approximation by an effective single band model close to the clean limit derived from a strongly coupled predominant hole subsystem with small Fermi velocities. However, in order to account also for Hall-conductivity and thermopower data in the literature, an effective general two-band model is proposed. This two-band model provides a flexible enough frame to describe consistently all available data within a scenario of phonon mediated s-wave superconductivity somewhat suppressed by sizeable electron-paramagnon or electron-electron Coulomb interaction. For quantitative details the relevance of soft phonons and of a van Hove type singularity in the electronic density of states near the Fermi energy is suggested.

21 pages, 26 figures (high quality version of figures 2,11 available at http://www.ifw-dresden.de/imw/21/coworker/waelte.priv/)

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• Superconductivity Near Ferromagnetism in MgCNi3
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• BCS-like Superconductivity in MgCNi3
• Electronic structure, magnetism and superconductivity of MgCNi${}_3$
• Low-Field Anomaly in the Specific Heat of s-wave Superconductors due to the Expansion of the Vortex Cores
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• The suppression of superconductivity in MgCNi3 by Ni-site doping
• Superconductivity near the vibrational mode instability in MgCNi3
• Influence of Carbon Concentration on the Superconductivity in MgCxNi3
• Pressure-dependence of electron-phonon coupling and the superconducting phase in hcp Fe - a linear response study
• Phonon spectrum and soft-mode behavior of MgCNi_3
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• Temperature dependence of the structural parameters of the non-oxide perovskite superconductor MgCNi3
• Superconducting Properties of MgCNi3 Films

Cited by in corpus (20)

• A review of two-band superconductivity: materials and effects on the thermodynamic and reversible mixed-state properties
• Thermodynamics of Two - Band Superconductors: The Case of MgB${}_2$
• Orbital and spin effects for the upper critical field in As deficient disordered Fe pnictide superconductors
• Strong electron-phonon coupling in the rare-earth carbide superconductor La2C3
• Low temperature transition to a superconducting phase in boron-doped silicon films grown on (001)-oriented silicon wafers
• Critical temperature and giant isotope effect in presence of paramagnons
• Multi-band conductivity and multi-gap superconductivity in V3Si from optical measurements on films at terahertz frequencies
• Evidence of multiband superconductivity in the $\beta$-phase Mo${}_{1-x}$Re${}_x$ alloys
• Optical Study of LaO_0.9F_0.1FeAs: Evidence for a Weakly Coupled Superconducting State
• Strong electron-phonon coupling and multiband effects in the superconducting $\beta$-phase Mo${}_{1-x}$Re${}_x$ alloys
• Competition between the BCS superconductivity and ferromagnetic spin fluctuations in MgCNi${}_3$
• S-wave superconductivity probed by measuring magnetic penetration depth and lower critical field of MgCNi${}_3$ single crystals
• Superconducting energy gap in MgCNi3 single crystals: Point-contact spectroscopy and specific-heat measurements
• The role of carbon for superconductivity in MgC${}_x$Ni${}_3$ from specific heat
• Role of C in MgC_xNi_3 investigated from first principles
• A first-principles comparison of the electronic properties of MgC_{y}Ni_{3} and ZnC_{y}Ni_{3} alloys
• Prediction of superconductivity of $3d$ transition-metal based antiperovskites via magnetic phase diagram
• Vacancies, disorder-induced smearing of the electronic structure, and its implications for the superconductivity of anti-perovskite MgC${}_{0.93}$Ni${}_{2.85}$
• Optical properties of $MgCN{i}_3$ in the normal state
• Superconductivity in the vicinity of ferromagnetism in oxygen free perovskite MgCNi3: An experimental and DFT (Density Functional Theory) study