(Fe,Sn)4N alloy as a model spin-glass system with short-range competing interactions on a nonfrustrated simple cubic lattice

TL;DR

This study investigates the spin-glass behavior in (Fe,Sn)4N alloys using first-principles calculations, revealing that short-range competing interactions on a simple cubic lattice can induce spin-glass states without geometric frustration.

Contribution

It demonstrates that (Fe,Sn)4N alloys serve as a minimal model for spin-glass systems with short-range competing interactions on a nonfrustrated lattice, excluding geometric frustration.

Findings

Short-range magnetic interactions dominate in (Fe,Sn)4N.

Spin-glass behavior arises from competing interactions, not geometric frustration.

The alloy provides a simplified framework to study spin-glass mechanisms.

Abstract

The origin of the spin-glass state in (Fe,Sn)4N alloys is studied on the basis of a Heisenberg Hamiltonian with parameters derived from first principles within the magnetic force theorem applied in the framework of the disordered local moments method and local spin-density approximation. We show that in the alloy concentration range where the spin-glass state is stable only one Fe sublattice is intrinsically magnetic and the interatomic exchange magnetic interactions are essentially short ranged due to effects of chemical and magnetic disorder. The magnetic Fe atoms with well-localized spin moments are randomly distributed over the nongeometrically frustrated simple cubic lattice. The magnetic frustration, which generally is believed to be an essential ingredient of the spin-glass state formation condition, may occur only due to the competition of the two nearest-neighbor interactions. We thus argue that (Fe,Sn)4N is a rare example of a spin-glass system where the mechanism of spin-glass state formation might be studied in the framework of the minimal random-site model on a simple cubic lattice with competing interactions, while the effects of the geometrical frustration can be excluded.