Speaker
Description
Scanning nitrogen-vacancy (NV) magnetometry is a powerful technique for nanoscale magnetic imaging. In this approach, the conventional atomic force microscopy tip is replaced by a diamond nanopillar containing a single NV center, which serves as a highly sensitive local magnetic field sensor. By scanning the NV center over a sample, the magnetic stray field can be mapped with high spatial resolution. While this technique has been widely applied at room temperature to study, for example, magnetic textures in thin films and local current flow patterns, many phenomena of interest—including emergent magnetic phases and superconductivity—only appear at cryogenic temperatures. As the NV center retains its ability to sense magnetic fields at low temperatures, we have been working towards a variable temperature cryogenic scanning NV system. This platform enables nanoscale magnetic imaging of materials at low temperature and offers a unique opportunity to directly probe magnetic phase transitions in quantum materials.
We have recently obtained our first low-temperature magnetic field maps at 7 K, and are now applying the technique to our first target system: single-molecule magnets. These molecules exhibit magnetic hysteresis at low temperatures, making them promising candidates for applications in information storage, molecular spintronics, and quantum computing [1]. The ability of our setup to operate over a broad range of temperatures and timescales makes it well suited for studying the strongly temperature-dependent behaviour of these molecules.
In this poster, we discuss our cryogenic scanning NV magnetometry setup, including experimental challenges associated with low-temperature operation, and present our first measurements on the single-molecule magnet Tb₂@C₈₀(CF₃)-Ih acquired at 7.5 K.
[1] Liu, F., Krylov, D., Spree, L. et al. Nat Commun 8, 16098, (2017)
