L. Rondin, J. P. Tetienne, S. Rohart, A. Thiaville, T. Hingant, P. Spinicelli, J. -F. Roch, V. Jacques
Nanostructured ferromagnetic thin films exhibiting a vortex state are of great interest both for fundamental studies and for applications such as non-volatile magnetic storage and microwave generation. Although magnetic vortex structures have been investigated using a wide range of microscopy techniques, obtaining quantitative information that is directly comparable to theory remains a challenging task. Further, imaging the vortex core, which can be as small as 10 nm and plays a crucial role in the vortex dynamics, is a long-standing goal that has been reached by very few methods only. Here we use a recently reported scanning probe magnetometer based on a single Nitrogen-Vacancy (NV) defect in diamond to quantitatively map the stray field above a thin ferromagnetic square in a vortex state. Owing to an unprecedented access to weak magnetic fields combined with an atomic-sized detection volume, scanning NV magnetometry reveals in 3D the full structure of the magnetic field distribution, including the detection of the vortex core. Furthermore, we show that the vectorial and quantitative nature of the measurement enable direct comparisons with micromagnetic simulations. This work thus opens new avenues for nanomagnetism and spintronics studies.
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http://arxiv.org/abs/1302.7307
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