Complex magnetic structure and spin waves of the noncollinear antiferromagnet Mn5Si3

TL;DR

This study explores the complex magnetic structure and spin wave behavior of Mn5Si3, combining experimental neutron scattering and theoretical calculations to understand its noncollinear antiferromagnetic state and field-induced phase transitions.

Contribution

It provides detailed insights into the magnetic exchange interactions, spin configurations, and magnon dispersions of Mn5Si3, revealing how magnetic moments can be tuned by external fields.

Findings

Magnon dispersion relations match experimental data

Multiple magnetic phase transitions under external magnetic fields

Magnetic moments in frustrated arrangements are field-tunable

Abstract

The investigations of the interconnection between micro- and macroscopic properties of materials hosting noncollinear antiferromagnetic ground states are challenging. These forefront studies are crucial for unraveling the underlying mechanisms at play, which may prove beneficial in designing cutting edge multifunctional materials for future applications. In this context, Mn5Si3 has regained scientific interest since it displays an unusual and complex ground state, which is considered to be the origin of the anomalous transport and thermodynamic properties that it exhibits. Here, we report the magnetic exchange couplings of the noncollinear antiferromagnetic phase of Mn5Si3 using inelastic neutron scattering measurements and density functional theory calculations. We determine the ground-state spin configuration and compute its magnon dispersion relations which are in good agreement with the ones obtained experimentally. Furthermore, we investigate the evolution of the spin texture under the application of an external magnetic field to demonstrate theoretically the multiple field-induced phase transitions that Mn5Si3 undergoes. Finally, we model the stability of some of the material's magnetic moments under a magnetic field and we find that very susceptible magnetic moments in a frustrated arrangement can be tuned by the field.