IMAGINE · Non-Invasive Imaging of Nanoscale Electronic Transport

Electronic transport in nanostructures and thin films shows a rich variety of physical effects that have been fundamental to the development of modern electronics and communication devices. The standard method for investigating electronic transport – resistance measurements – does not provide any information on the nanoscale current distribution in such structures. The lack of spatial information is unfortunate, because the current distribution plays a key role in many intriguing physical phenomena. Having a technique at hand that could simply look at nanoscale current flow would be immensely valuable.In this project we propose to exploit sensitive magnetic microscopy to directly access the current distribution in nanostructures with ~15nm spatial resolution. Our approach is based on the recent technique of scanning diamond magnetometry (SDM), a scanned-probe method that utilizes a single spin in a diamond tip as a high-resolution sensor of magnetic field. Conceived in 2008 by the PI, SDM exploits quantum metrology to achieve very high sensitivities, and has recently enabled a breakthrough in the passive analysis of magnetic surfaces. Our proposal has three objectives: (i) Lay the instrumental and conceptual groundwork required for imaging tiny (<10nA) current variations in two-dimensional conductors. (ii) Demonstrate imaging of a variety of mesoscopic transport features on a well-established model system: Mono- and bilayer graphene. (iii) Explore the potential of our technique for probing electronic properties beyond transport, like phase transitions and photoexcitation.Together, our experiments are designed to establish a powerful new technology for imaging current distributions non-invasively and with nanometer spatial resolution. This capability will provide the unique opportunity for directly looking at electronic transport in nanostructures, with a potentially transformative impact on condensed matter physics, materials science and electrical engineering.