Influence of interstitial Mn on magnetism in room-temperature ferromagnet Mn(1+delta)Sb

TL;DR

This study investigates how interstitial Mn ions affect the magnetic properties of Mn(1+delta)Sb, revealing their magnetic nature and impact on magnetic excitations through neutron scattering and theoretical calculations.

Contribution

It provides new insights into the magnetic role of interstitial Mn in Mn(1+delta)Sb, combining neutron scattering experiments with density functional theory.

Findings

Interstitial Mn has a magnetic moment aligned antiparallel to main Mn.

Magnetic dynamics show spin-wave-like dispersion and broad signals.

Interstitial Mn significantly alters magnetic excitations.

Abstract

We report elastic and inelastic neutron scattering measurements of the high-TC ferromagnet Mn(1+delta)Sb. Measurements were performed on a large, TC=434 K, single crystal with interstitial Mn content of delta~0.13. The neutron diffraction results reveal that the interstitial Mn has a magnetic moment, and that it is aligned antiparallel to the main Mn moment. We perform density functional theory calculations including the interstitial Mn, and find the interstitial to be magnetic in agreement with the diffraction data. The inelastic neutron scattering measurements reveal two features in the magnetic dynamics: i) a spin-wave-like dispersion emanating from ferromagnetic Bragg positions (H K 2n), and ii) a broad, non-dispersive signal centered at forbidden Bragg positions (H$\,$K$\,$2$n$+1). The inelastic spectrum cannot be modeled by simple linear spin-wave theory calculations, and appears to be significantly altered by the presence of the interstitial Mn ions. The results show that the influence of the interstitial Mn on the magnetic state in this system is more important than previously understood.