Nanoscale single spin magnetometry of thin-film (anti-)ferromagnets down to the monolayer limit
Prof. Dr. Patrick Maletinsky (Department of Physics, University of Basel)

Electronic spins yield excellent quantum sensors [1], offering quantitative sensing [2] and nanoscale imaging [3] down to the level of single spins [4]. Over the last years, the Basel Quantum Sensing Group has developed all-diamond scanning probes [5,6], hosting individual Nitrogen-Vacancy (NV) centre electronic spins as nanoscale magnetometers, to address open problems in condensed matter physics. I will describe our recent advances in applying this novel and unique quantum-sensing technology to study nano-magnetism in a variety of systems at room temperature and under cryogenic conditions [7].
Specifically, I will discuss applications of NV magnetometry in the emerging fields of antiferromagnetic spintronics [8] and magnetism in two-dimensional van der Waals materials [9]. In the former case, we demonstrated imaging of nanoscale antiferromagnetic domains in granular thin films of Cr2O3 [10] to explore the mechanism of domain formation and determine the strength of the inter-granular exchange coupling [10] - a key parameter for all technologically relevant thin films magnets. Atomic monolayers form an ultimate limit for such thin films and the recent discovery of magnetism in a range of van der Waals materials has therefore attracted significant interest. I will discuss how we shed new light on several key open aspects of the physics of these materials by employing quantitative NV magnetometry to study CrI3 magnetism down to the monolayer limit. Specifically, we provided the first direct determination of the saturation magnetisation in few layer CrI3 and elucidate the nature of the interlayer exchange coupling in this material. These results show the high potential for pushing further the frontiers of antiferromagnetic spintronics and two-dimensional magnetism by quantum sensing with NV centre spins.

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