Magnetoelectric behavior in metal-organic complexes including spin crossovers compounds

We explore metal-organic complexes that show unconventional routes to magnetoelectric behavior. Traditionally, magnetoelectric behavior has been most commonly studied in inorganic oxides, where ferro or antiferromagnetism couples to dielectric or ferroelectric properties. Such coupling allows an electric field to control and switch e.g. a quantum magnetic state or vice versa. This field contains a wealth of intriguing fundamental science, as well as applications being targeted in ultra-low power sensing, qubits, memories, tunable antennas, and other devices. In this talk I will review several of our recent efforts to extend this field of magnetoelectrics to metal-organic complexes, which contain transition metal ions and organic ligands. These compounds tend to have soft lattices that mediate magnetoelectric coupling, and a broad array of intriguing forms of magnetism going beyond (anti) ferromagnetism. I will begin with spin crossovers where the spin state of a transition metal ion changes with applied magnetic fields, thereby modifying the electric polarization. I will show results on Mn-based spin crossovers where magnetic fields toggle the spin state and thereby induce structural phase transitions or Jahn Teller effects. These structural changes result in very strong magnetoelectric coupling as well as complex phase diagrams. I will also discuss metal-organic frameworks that are effectively intrinsic heterostructures where magnetic and electric properties can be combined with flexible architectures. I will review the state of this nascent field and potential new directions.