Multi-modal imaging of condensed matter systems with quantum diamond microscopy

Full text: Solid-state quantum sensors are an emerging technology that is well suited to applications in condensed matter physics, thanks to their unprecedented combination of small size, sensitivity and robustness. In particular, the nitrogen-vacancy (NV) defect centre in diamond has become one of the most popular platforms for quantum sensing and especially for magnetometry, as illustrated by the recent demonstration by our group of current flow imaging in graphene using a quantum diamond microscope. Here we show that it is possible to integrate other sensing modalities to this quantum diamond microscope, namely electric field and strain sensing. On the one hand, imaging the electric field at the diamond surface allows us to study the surface band bending from different surface terminations and then from a two-terminal device based on the two-dimensional hole gas formed at the surface of hydrogen-terminated diamond. On the other hand, we show that the full stress tensor can be mapped with sub-micron resolution, and we apply this capability to the quantitative imaging of elastic deformation in the diamond induced by localized implantation damage, nano-indents, scratches as well as from functional electronic devices fabricated on the diamond. The addition of new sensing modes to quantum diamond microscopy opens up new opportunities for the study of condensed matter systems. (author)