# Discovery of Weyl nodal lines in a single-layer ferromagnet

## TL;DR

This paper reports the discovery of symmetry-protected Weyl nodal lines in a single-layer ferromagnetic gadolinium-silver compound, combining experimental and theoretical methods, which could advance 2D magnetic topological materials and spintronic devices.

## Contribution

It presents the first observation of Weyl nodal lines in a 2D ferromagnetic material, demonstrating their robustness and potential for novel quantum device applications.

## Key findings

- Weyl nodal lines are symmetry protected and robust.
- Discovery based on combined spectroscopy and theoretical calculations.
- Coexistence of magnetic and topological order in 2D material.

## Abstract

Two-dimensional (2D) materials have attracted great attention and spurred rapid development in both fundamental research and device applications. The search for exotic physical properties, such as magnetic and topological order, in 2D materials could enable the realization of novel quantum devices and is therefore at the forefront of materials science. Here, we report the discovery of two-fold degenerate Weyl nodal lines in a 2D ferromagnetic material, a single-layer gadolinium-silver compound, based on combined angle-resolved photoemission spectroscopy measurements and theoretical calculations. These Weyl nodal lines are symmetry protected and thus robust against external perturbations. The coexistence of magnetic and topological order in a 2D material is likely to inform ongoing efforts to devise and realize novel nanospintronic devices.