Vibrational and magnetic signatures of extended defects in Fe

摘要

Defects change the phonon spectrum and also the magnetic properties of bcc-Fe. Using molecular dynamics simulation, the influence of defects - vacancies, dislocations, and grain boundaries - on the phonon spectra and magnetic properties of bcc-Fe is determined. It is found that the main influence of defects consists in a decrease of the amplitude of the longitudinal peak, P-L, at around 37 meV. While the change in phonon spectra shows only little dependence on the defect type, the quantitative decrease of P-L is proportional to the defect concentration. Local magnetic moments can be determined from the local atomic volumes. Again, the changes in the magnetic moments of a defective crystal are linear in the defect concentrations. In addition, the change of the phonon density of states and the magnetic moments under homogeneous uniaxial strain are investigated.