Direct Imaging and Manipulation of Antiferromagnets

ended

Antiferromagnetic materials are very promising candidates for the development of new data storage devices with a low power comsumption, which explains the recent growing interest for the field of antiferromagnetic spintronics. However, the study of these systems is hindered by the difficulty to image their magnetic state in real space with most of the available microscopy techniques. The recently developed nitrogen-vacancy (NV) center magnetometry appears to be a solution to this problem. It probes the magnetic order via the measurement of the stray field present at the surface of the sample. The field is measured using the Zeeman shifts of the electronic spin sublevels of a single nitrogen-vacancy defect in diamond. The single NV defect is placed at the apex of a nanopillar in a diamond tip integrated into an atomic force microscope, allowing to scan in close proximity to the sample surface. The goal of this project is to use this technique to explore the magnetic order at the nanoscale in antiferromagnetic materials which are relevant for applications in spintronics. The magnetic configuration of the modulated antiferromagnet BiFeO3 will be investigated. The experiments will first focus on the effects of epitaxial strain on the antiferromagnetic order. In a second step, the antiferromagnetic structure will be manipulated with local strain and spin currents. The NV-center magnetometer will be used to image directly the induced modifications. This project offers high-quality technical training in NV-center magnetometry as well as the opportunity to acquire and strengthen transferable skills and to participate to international collaborations. It will thus foster the career development of the researcher in the growing and highly innovative field of antiferromagnetic spintronics.