Résumé
Antiferromagnets attract a great interest for spintronics owing to the robustness of the hosted magnetic textures and their fast dynamics. NV-center magnetometry has emerged in the last years as a powerful technique to investigate them. Here we introduce a new imaging mode of the NV magnetometer which relies on the detection of noise originating from spin waves interacting with the textures of interest.We demonstrate this method on synthetic antiferromagnets (SAF). We first image domain walls and prove that we perform noise-based imaging by measuring spin relaxation times. Calculations of the spin wave dispersions as well as maps of simulated noise intensity enable us to conclude that we probe spin waves channelled in the domain walls. Going further, we tune the composition of the SAF stacks in order to stabilize spin spirals or skyrmions. In both cases, our relaxometry-based technique is able to image the non-collinear structures, demonstrating its efficiency and opening new avenues of exploration in the characterization of complex structures in magnetically-compensated materials.This work was done in collaboration with the UMR CNRS/Thalès and the C2N in Palaiseau, France. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 846597 and from the DARPA TEE Program.