Kohn anomalies in momentum dependence of magnetic susceptibility of some three-dimensional systems

Resumo

We study a question of the presence of Kohn points, yielding at low temperatures nonanalytic momentum dependence of magnetic susceptibility near its maximum, in electronic spectra of some threedimensional systems. In particular, we consider a one-band model on face-centered cubic lattice with hopping between the nearest and next-nearest neighbors, which models some aspects of the dispersion of ZrZn₂, and the two-band model on body-centered cubic lattice, modeling the dispersion of chromium. For the former model, it is shown that Kohn points yielding maxima of susceptibility exist in a certain (sufficiently wide) region of electronic concentrations; the dependence of the wave vectors, corresponding to the maxima, on the chemical potential is investigated. For the two-band model, we show the existence of the lines of Kohn points, yielding maximum susceptibility, whose position agrees with the results of band structure calculations and experimental data on the wave vector of antiferromagnetism of chromium.