title: Vectorial scanning force microscopy using a nanowire sensor.
abstract: Self-assembled nanowire (NW) crystals can be grown into nearly defect-free nanomechanical resonators with exceptional properties, including small motional mass, high resonant frequency and low dissipation. Furthermore, by virtue of slight asymmetries in geometry, a NW's flexural modes are split into doublets oscillating along orthogonal axes. These characteristics make bottom-up grown NWs extremely sensitive vectorial force sensors. Here, taking advantage of its adaptability as a scanning probe, we use a single NW to image a sample surface. By monitoring the frequency shift and direction of oscillation of both modes as we scan above the surface, we construct a map of all spatial tip-sample force derivatives in the plane. Finally, we use the NW to image electric force fields distinguishing between forces arising from the NW charge and polarizability. This universally applicable technique enables a form of atomic force microscopy particularly suited to mapping the size and direction of weak tip-sample forces.
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Rossi
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
authors.forename: Floris R
authors.initials: FR
authors.lastname: Braakman
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
authors.forename: Davide
authors.initials: D
authors.lastname: Cadeddu
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
authors.forename: Denis
authors.initials: D
authors.lastname: Vasyukov
authors.affiliation: Laboratoire des Matériaux Semiconducteurs, Institut des Matériaux, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Gözde
authors.initials: G
authors.lastname: Tütüncüoglu
authors.affiliation: Laboratoire des Matériaux Semiconducteurs, Institut des Matériaux, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Fontcuberta I Morral
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
authors.forename: Martino
authors.identifier: 0000-0002-5327-051X
authors.initials: M
authors.lastname: Poggio