Realm of Spin State Switching Materials: Toward Realization of Molecular and Nanoscale Devices

For various technological applications involving the design of molecular- and nanoscale devices, spin crossover (SCO) materials are a way forward owing to an ability to have a readout in the form of distinct changes in physical properties accompanying the stimuli-responsive spin-state modifications. In particular, iron-based molecular SCO systems are of great interest as they have shown vast potential applications in the design of functional devices, including sensors and electrical, optical, mechanical, spintronic, memory storage, and processing devices. Due to the inherent fragility of SCO systems, several factors, such as substrate selection, electrode materials (in the case of electronic devices), and molecule-substrate interactions, must be carefully considered while integrating SCO systems into functional devices. To ensure reliable device performance, the compatibility of SCO complexes with the techniques used to fabricate devices is also crucial. Considering these factors, the major aim of this Perspective is to concisely represent a part of our research work on this broad up-and-coming topic, mentioning the relevance of spin crossover materials, and provide an overview to the reader about the recent developments, achievements, and advancements of micro- and nanoscale devices based on the phenomena of spin-state switching, which in turn is highly versatile. A particular emphasis is given to the SCO systems used for thin films, nanoparticles, and molecule-based devices, highlighting the challenges and prospects associated with each approach.