Theory of the ferromagnetism in TiCrN solid solutions

TL;DR

This paper uses first-principles calculations to explore how alloying TiN with CrN induces ferromagnetism in TiCrN solid solutions by altering magnetic interactions and electron density distribution.

Contribution

It reveals the mechanism behind ferromagnetism emergence in TiCrN alloys, linking electron redistribution to magnetic property changes, supported by theoretical calculations.

Findings

Ferromagnetism appears at x ≤ 0.50 in TiCrN alloys.

Electron density redistribution from Ti to Cr influences magnetic states.

Changes in Cr d-state polarization favor ferromagnetic interactions.

Abstract

First-principles calculations are used to investigate the magnetic properties of Ti$_{1-x}$Cr$_{x}$N solid solutions. We show that the magnetic interactions between Cr spins that favour antiferromagnetism in CrN is changed upon alloying with TiN leading to the appearance of ferromagnetism in the system at approximately $x \leq 0.50$ in agreement with experimental reports. Furthermore we suggest that this effect originates in an electron density redistribution from Ti to Cr that decreases the polarization of Cr d-states with t$_{2g}$ symmetry while it increases the polarization of Cr d-states with e$_g$ symmetry, both changes working in favour of ferromagnetism.