Imaging Magnetic Skyrmions Under Ambient Conditions with an Atomic-Sized Sensor

Magnetic skyrmions are particle-like topologically-protected spin structures, which commonly crystallize in chiral magnets at cryogenic temperatures. Recently stable room-temperature skyrmions were reported in stacks of thin magnetic films[1,2]. Establishing the microscopic structure of these skyrmions in the presence of external magnetic fields is a key experimental challenge, calling for a quantitatve room-temperature approach. We use a scanning Nitrogen-Vacancy (NV) center to image skyrmions at a Pt/CoFeB interface as well as in Pt/Co/Ta multilayers in ambient conditions[3]. We perform full vector magnetometry of the local magnetic fields produced by the films. We establish the presence of a N\'{e}el-type skyrmion. In addition to static magnetic signal, we discover a modulation of the NV spin transition linewidth suggesting the presence of thermal fluctuations of the spin structure. Our results identify NV magnetometry as a promising local probe for both static magnetization structures and spin fluctuations in a variety of low-dimensional condensed matter systems. [1] Woo, S. \textit{et al.} \textit{Nat. Mater.} \textbf{15,} 501--506 (2016). [2] Moreau-Luchaire, C. \textit{et al.} \textit{Nat. Nanotechnol.} \textbf{11,} 444--448 (2016). [3] Dovzhenko*, Y., Casola*, F. \textit{et al.} arxiv:1611.00673 (2016).