Optical Control of Electrical Properties in Molecular Crystals ---- States of Matter beyond Thermodynamic Restrictions

Molecular crystals are among the states of matter containing the largest number of thermodynamic degrees of freedom concerning spin, charge, orbital, and structure. However, many of them cannot be fully controlled to realize the unique physical properties and novel electronic states because of the thermodynamic instability of the molecular crystals. We will review here the evidence that optical excitation is a powerful tool, independent of thermodynamic conditions, to realize unique physical properties and electronic states otherwise unrealized.