Numerical Studies on the Magnetism of Fe-Ni-Mn Alloys in the Invar Region

TL;DR

This study uses semi-empirical calculations to explore the complex local magnetic behaviors and electrical conductance of Fe-Ni-Mn alloys in the Invar region, revealing both ferromagnetic and spin-glass-like states.

Contribution

It provides a detailed theoretical analysis of local magnetism and electrical conductance in Fe-Ni-Mn alloys, including metastable states and comparison with experimental data.

Findings

Presence of ferromagnetic and spin-glass-like configurations

Reproduction of experimental y-dependence of resistivity

Identification of discrepancies in resistivity magnitude

Abstract

By means of self-consistent semi-empirical LCAO calculations we study the itinerant magnetism of (Fe_{0.65}Ni_{0.35})_{1-y} Mn_y alloys for y between 0 and 0.22 at T=0 K, neglecting only the transverse spin components. We find that the magnetic behaviour is quite complicated on a local scale. In addition to ferromagnetic behaviour, also metastable spin-glass-like configurations are found. In the same approach, using a direct numerical calculation by the Kubo-Formalism without any fit parameters, we also calculate the electrical conductance in the magnetic state and find that the $y$-dependence observed in the experiments is well reproduced by our calculations, except of an overall factor of rougly 5, by which our resistivities are too large.