Vacancies, disorder-induced smearing of the electronic structure, and its implications for the superconductivity of anti-perovskite MgC0.93Ni2.85

Abstract

The anti-perovskite superconductor MgC0.93Ni2.85 was studied using high-resolution x-ray Compton scattering combined with electronic structure calculations. Compton scattering measurements were used to determine experimentally a Fermi surface that showed good agreement with that of our supercell calculations, establishing the presence of the predicted hole and electron Fermi surface sheets. Our calculations indicate that the Fermi surface is smeared by the disorder due to the presence of vacancies on the C and Ni sites, but does not drastically change shape. The 20% reduction in the Fermi level density-of-states would lead to a significant (~70%) suppression of the superconducting T c for pair-forming electron-phonon coupling. However, we ascribe the observed much smaller T c reduction at our composition (compared to the stoichiometric compound) to the suppression of pair-breaking spin fluctuations.

Electron Localization Function and Compton Profiles of Cu2O

“…We apply the linearized augmented plane-wave (LAPW) method within the framework of density functional theory (DFT) to study ELF, CP, and the anisotropies in the DCPs of Cu 2 O. − It is worth noting that only recently has it become possible to calculate the CP using the LAPW method. , Interestingly, for Cu 2 O, the experimental profile is reported by Bandopadhyay et al, so we compare our calculations with the measurement . Calculations of the CP using the local density approximation (LDA) and Lee–Yang–Par exchange and correlation (XC) functionals are reported using the linear combination of Gaussian orbital (LCGO) and the linear combination of atomic orbital (LCAO) methods, respectively, by previous workers. , The LCGO calculations are performed at the experimental lattice constant on a grid of few points to sample the irreducible Brillouin zone, which affects the accuracy of calculated CPs and anisotropies .…”

“…32−34 It is worth noting that only recently has it become possible to calculate the CP using the LAPW method. 14,34 Interestingly, for Cu 2 O, the experimental profile is reported by Bandopadhyay et al, so we compare our calculations with the measurement. 35 Calculations of the CP using the local density approximation (LDA) and Lee−Yang−Par exchange and correlation (XC) functionals are reported using the linear combination of Gaussian orbital (LCGO) and the linear combination of atomic orbital (LCAO) methods, respectively, by previous workers.…”

Temperature-Responsive Photoluminescence and Elastic Properties of 1D Lead Halide Perovskites R- and S-(Methylbenzylamine)PbBr3

“…Metal halide perovskites (MHPs) are attracting considerable interest owing to their excellent optoelectronic properties tunable at a molecular level [ 1 , 2 , 3 , 4 , 5 ]. The merits of a high absorption coefficient, good defect resistance, and ease of synthesis [ 6 , 7 , 8 ] have led to their wide application in solar cells [ 9 , 10 , 11 , 12 ], photodetectors [ 13 , 14 , 15 ], and light-emitting diodes [ 16 , 17 , 18 , 19 , 20 , 21 ].…”

Magnetic Compton profiles of Ni beyond the one-particle picture: numerically exact and perturbative solvers of dynamical mean-field theory

“…Thus Compton scattering is a uniquely powerful probe of the ground state many-body wavefunction [3]. In recent years, Compton scattering has been used to reveal the electronic structure and Fermi surfaces [4] in electronically complex materials such as substitutionally disordered alloys [5,6] and compounds with high vacancy concentrations [7]. Most relevantly, Compton scattering is able to probe the electron correlations within many complex materials [8][9][10][11].…”