Switching on Organic Magnets with Light

Controlling magnetism using light—rather than electricity—could revolutionise fields like spintronics, data storage, and quantum computing. A recent review highlights the potential of all-organic bistable spin systems for this task. These organic materials are advantageous over traditional transition metal-based systems because they possess weak spin-orbit coupling and low hyperfine interactions, properties that theoretically favour stable spin states.

However, using light as a stimulus to control these molecular spin states is difficult and remains in the early stages of development. The most promising method involves photochemical reactions, but a major hurdle persists: accessing the magnetically active 'triplet state'. In most cases, the material sits in a non-magnetic 'singlet state' (the ground state). The energy gap required to jump to the excited triplet state is often too high to bridge easily. Scientists are now analysing these photochromic magnetic materials to recommend new compositions that can overcome this energy barrier and enable efficient photonic switching.