We report the development of a scanning force microscope based on an ultrasensitive silicon nitride membrane optomechanical transducer. Our development is made possible by inverting the standard microscope geometry-in our instrument, the substrate is vibrating and the scanning tip is at rest. We present topography images of samples placed on the membrane surface. Our measurements demonstrate that the membrane retains an excellent force sensitivity when loaded with samples and in the presence of a scanning tip. We discuss the prospects and limitations of our instrument as a quantum-limited force sensor and imaging tool.

We demonstrate the use of individual magnetic nanowires (NWs), grown by focused electron beam induced deposition (FEBID), as scanning magnetic force sensors. Measurements of their mechanical susceptibility, thermal motion, and magnetic response show that the NWs posses high-quality flexural mechanical modes and a strong remanent magnetization pointing along their long axis. Together, these properties make the NWs excellent sensors of weak magnetic field patterns, as confirmed by calibration measurements on a micron-sized current-carrying wire and magnetic scanning probe images of a permalloy disk. The flexibility of FEBID in terms of the composition, geometry, and growth location of the resulting NWs, makes it ideal for fabricating scanning probes specifically designed for imaging subtle patterns of magnetization or current density. arXiv:1911.00912v1 [cond-mat.mes-hall] 3 Nov 2019Recently, a form of magnetic force microscopy (MFM) based on a transducer made from a magnet-tipped nanowire (NW) demonstrated a high sensitivity to magnetic field gradients of 11 mT/(m √ Hz) with a similar spatial resolution 9 . The high force sensitivity of NW cantilevers coupled together with a small magnetic tip size could allow such sensors to work both close to a sample, maximizing spatial resolution, and in a regime of weak interaction, remaining noninvasive.Here, we demonstrate the use of individual magnetic NWs, patterned by focused electron beam induced deposition (FEBID), as MFM transducers for mapping magnetic fields with high sensitivity and resolution. The monopole-like magnetic charge distribution of their tips makes these transducers directly sensitive to magnetic fields rather