Local electron-electron interaction strength in ferromagnetic nickel determined by spin-polarized positron...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Ferromagnetic materials like nickel exhibit complex electronic correlations.
• Understanding these correlations is crucial for predicting material properties.

Purpose of the Study:

• To experimentally measure the spin-difference spectra of ferromagnetic nickel.
• To theoretically model electronic correlations using LSDA and DMFT.
• To determine the strength of local electronic interaction (U) in nickel.

Main Methods:

• Utilized spin-polarized two-dimensional angular correlation of annihilation radiation (2D-ACAR) for experimental measurements.
• Employed a combination of local spin density approximation (LSDA) and many-body dynamical mean-field theory (DMFT) for theoretical calculations.
• Compared experimental data with theoretical results.

Main Results:

• The self-energy, which defines electronic correlations, introduces anisotropic contributions to the momentum distribution in nickel.
• Direct comparison between experimental and theoretical data allowed for precise determination of U.
• The local electronic interaction strength (U) in ferromagnetic nickel was found to be 2.0 ± 0.1 eV.

Conclusions:

• The study successfully combined experimental and theoretical approaches to investigate electronic correlations in nickel.
• The determined value of U provides critical insight into the electronic behavior of ferromagnetic nickel.
• This work validates the use of LSDA+DMFT in describing correlated electron systems.