Electron-phonon coupling in Ni-based binary alloys with application to displacement cascade modeling.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Energy transfer between lattice atoms and electrons is crucial for understanding material behavior under irradiation.
• Electron-phonon (el-ph) coupling strength governs this energy dissipation, particularly in displacement cascades.
• Accurate modeling of el-ph coupling is essential for predicting material performance and durability.

Purpose of the Study:

• To calculate the el-ph coupling in concentrated Ni-based alloys (NiFe, NiCo, NiPd, NiCr).
• To investigate the influence of magnetic ordering on el-ph coupling and its temperature dependence.
• To incorporate these findings into molecular dynamics simulations to assess their impact on defect production.

Main Methods:

• Utilized electronic structure calculations within the coherent potential approximation.
• Determined magnetic properties and density of states at the Fermi level for Ni-based alloys.
• Developed and applied a two-temperature model incorporating calculated el-ph coupling in cascade simulations.

Main Results:

• NiFe, NiCo, and NiPd alloys exhibit ferromagnetic ordering, while NiCr is nonmagnetic.
• Magnetic ordering, originating from Stoner-type magnetism, reduces el-ph coupling by approximately 50%.
• Calculated el-ph coupling increases with temperature initially, then decreases above the Curie temperature.

Conclusions:

• Magnetic state significantly reduces el-ph coupling in these Ni-based alloys.
• The temperature dependence of el-ph coupling is linked to the electronic density of states.
• Incorporating these el-ph coupling parameters in simulations enhances defect production predictions by 10-20%.