Janus graphene nanoribbons with localized states on a single zigzag edge.

Topological design of π electrons in zigzag-edged graphene nanoribbons (ZGNRs) leads to a wealth of magnetic quantum phenomena and exotic quantum phases. Symmetric ZGNRs typically show antiferromagnetically coupled spin-ordered edge states. Eliminating cross-edge magnetic coupling in ZGNRs not only enables the realization of a class of ferromagnetic quantum spin chains, enabling the exploration of quantum spin physics and entanglement of multiple qubits in the one-dimensional limit, but also establishes a long-sought-after carbon-based ferromagnetic transport channel, pivotal for ultimate scaling of GNR-based quantum electronics.

Decoding the surface of a complex oxide.

Atomic force microscopy reveals the elusive structure of the aluminum oxide surface.

Exploring in-plane interactions beside an adsorbed molecule with lateral force microscopy.

Atomic force microscopy with a CO-functionalized tip can be used to directly image the internal structure of a planar molecule and to characterize chemical bonds. However, hydrogen atoms usually cannot be directly observed due to their small size. At the same time, these atoms are highly important, since they can direct on-surface chemical reactions.

On the origin and elimination of cross coupling between tunneling current and excitation in scanning probe experiments that utilize the qPlus sensor.

The qPlus sensor allows for the simultaneous operation of scanning tunneling microscopy (STM) and atomic force microscopy (AFM). When operating a combined qPlus sensor STM/AFM at large tunneling currents, a hitherto unexplained tunneling current-induced cross coupling can occur, which has already been observed decades ago. Here, we study this phenomenon both theoretically and experimentally; its origin is voltage drops on the order of μV that lead to an excitation or a damping of the oscillation, depending on the sign of the current.

Electrochemical AFM/STM with a qPlus sensor: A versatile tool to study solid-liquid interfaces.

Atomic force microscopy (AFM) that can be simultaneously performed with scanning tunneling microscopy (STM) using metallic tips attached to self-sensing quartz cantilevers (qPlus sensors) has advanced the field of surface science by allowing for unprecedented spatial resolution under ultrahigh vacuum conditions. Performing simultaneous AFM and STM with atomic resolution in an electrochemical cell offers new possibilities to locally image both the vertical layering of the interfacial water and the lateral structure of the electrochemical interfaces. Here, a combined AFM/STM instrument realized with a qPlus sensor and a home-built potentiostat for electrochemical applications is presented.