# Phase diagram of a magnetic topological nodal semimetal: Stable nodal line in an easy-plane ferromagnet

## TL;DR

This paper explores the phase diagram of a ferromagnetic topological nodal semimetal, revealing that an easy-plane magnetization stabilizes a nodal line phase acting as a boundary between Weyl semimetal phases.

## Contribution

It demonstrates the stability of a nodal line phase in a ferromagnetic topological semimetal under easy-plane magnetization, expanding understanding of topological phase boundaries.

## Key findings

- Nodal line structure is stable with easy-plane magnetization.
- Nodal line phase acts as a boundary between Weyl phases.
- Topology depends on magnetization direction.

## Abstract

We study a topological phase diagram of a ferromagnetic topological nodal semimetal. We consider a lattice model for three-dimensional topological insulators with ferromagnetic ordering. The exchange coupling between the magnetization and the electron spin leads to the nodal band structure. The topology of the nodal band structure depends on the direction of the magnetization and both the Weyl points and the nodal line emerge. We find that the nodal line structure is stable under an easy-plane magnetization in appropriate model parameters. In this case, the nodal line phase emerges as a phase boundary between two topologically distinct Weyl semimetal phases.