The investigation of the magnetoelectric effect in a cobalt-dioxolene complex under 60 T pulsed magnetic fields

Magnetic-field driven spin crossover (SCO) transitions provide an attractive route to realizing magnetoelectric (ME) coupling and reveal rich high-field phase diagrams with novel ME phases. Cobalt-dioxolene complexes have been shown to exhibit tautomeric SCO transitions, wherein a SCO occurs via electron transfer from the ligand to the central Co ion. This process creates a profound level of coupling between the spin state, the molecular electric dipole, and the chemical and lattice properties. These materials are promising candidates for a range of applications due to the range of mechanisms that can induce the SCO transition. Tautomeric transitions in cobalt-dioxolene complexes have been induced thermally, by visible light and X-Rays, by magnetic field and by pressure.

We report an investigation of the ME effect in a particular cobalt-dioxolene complex, Co(Cat)(SQ)(4-CNpy)₂, which exhibits a tautomeric SCO transition at around 110 K accompanied by a change in the electric dipole of the molecule. The magnetic moment and polarization have been measured as a function of temperature and applied magnetic field, both in DC fields up to 14 T and in pulsed fields up to 60 T in order to elucidate the high field phase diagram.