# Complex magnetism of B20-MnGe: from spin-spirals, hedgehogs to monopoles

## TL;DR

This study uses large-scale first-principles simulations to explore the complex magnetic phases of B20-MnGe, revealing a volume-dependent transition among ferromagnetic, spin-spiral, hedgehog, and monopole states.

## Contribution

It introduces a massively parallel all-electron density functional approach to accurately simulate large magnetic systems and map their phase transitions.

## Key findings

- Magnetic phase transitions depend on the compound volume.
- Multiple magnetic textures coexist, including hedgehogs and monopoles.
- First-principles simulations reveal the energetic hierarchy of phases.

## Abstract

B20 compounds are the playground for various non-trivial magnetic textures such as skyrmions, which are topologically protected states. Recent measurements on B20-MnGe indicate no clear consensus on its magnetic behavior, which is characterized by the presence of either spin-spirals or 3-dimensional objects interpreted to be a cubic lattice of hedgehogs and anti-hedgehogs. Utilizing a massively parallel linear scaling all-electron density functional algorithm, we find from full first-principles simulations on cells containing thousands of atoms that upon increase of the compound volume, the state with lowest energy switches across different magnetic phases: ferromagnetic, spin-spiral, hedgehog and monopole.