# The influence of antiphase boundary of the MnAl $\tau$-phase on the energy product

## TL;DR

This study investigates how antiphase boundary defects in MnAl τ-phase influence the energy product of permanent magnets, combining multiscale simulations and first-principles calculations to provide a comprehensive understanding.

## Contribution

It introduces a multiscale approach linking atomistic, micromagnetic, and first-principles methods to quantify defect effects on magnetic properties of MnAl τ-phase.

## Key findings

- Antiphase boundary defects reduce the energy product of MnAl τ-phase magnets.
- The exchange interaction across defects can be accurately estimated from first-principles calculations.
- Micromagnetic simulations reveal the impact of defect density on magnetic performance.

## Abstract

In this work we use a multiscale approach toward a realistic design of a permanent magnet based on MnAl $\tau$-phase and elucidate how the antiphase boundary defects present in this material affect the energy product. We show how the extrinsic properties of a microstructure depend on the intrinsic properties of a structure with defects by performing micromagnetic simulations. For an accurate estimation of the energy product of a realistic permanent magnet based on the MnAl $\tau$-phase with antiphase boundaries, we quantify for the first time the exchange interaction strength across the antiphase boundary defect with a simple approach derived from the first-principles calculations. These two types of calculations performed at different scales are linked via atomistic spin dynamic simulations performed at an intermediate scale.