  Future multi-functional hybrid devices might combine switchable molecules and
2D material-based devices. Spin-crossover compounds are of particular interest
in this context since they exhibit bistability and memory effects at room
temperature while responding to numerous external stimuli. Atomically-thin 2D
materials such as graphene attract a lot of attention for their fascinating
electrical, optical, and mechanical properties, but also for their reliability
for room-temperature operations. Here, we demonstrate that thermally-induced
spin-state switching of spin-crossover nanoparticle thin films can be monitored
through the electrical transport properties of graphene lying underneath the
films. Model calculations indicate that the charge carrier scattering mechanism
in graphene is sensitive to the spin-state dependence of the relative
dielectric constants of the spin-crossover nanoparticles. This graphene sensor
approach can be applied to a wide class of (molecular) systems with tunable
electronic polarizabilities.
