Laser-Induced Ferroelectric Structural Order in an Organic Charge-Transfer Crystal

• Published in: Science (American Association for the Advancement of Science) Vol. 300; no. 5619; pp. 612 - 615
• Main Authors: Collet, Eric, Lemée-Cailleau, Marie-Hélène, Cointe, Marylise Buron-Le, Cailleau, Hervé, Wulff, Michael, Luty, Tadeusz, Koshihara, Shin-Ya, Meyer, Mathias, Toupet, Loic, Rabiller, Philippe, Techert, Simone
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 25.04.2003; The American Association for the Advancement of Science
• Subjects: Broken symmetry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Crystallography; Crystals; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Diffraction; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Ferroelectricity and antiferroelectricity; Ferroelectrics; Irradiation; Lasers; Lattice dynamics; Materials; Molecular biology; Molecules; Neutrality; Observation; Phase transformations (Statistical physics); Phase transitions (Physics); Phase transitions and curie point; Physics; Solid-solid transitions; Specific phase transitions; Synchrotrons; Wave diffraction; X ray diffraction; X-ray crystallography; X-rays; France; Radiation effects; Phase transformations; Long-range order; TTF; Molecular crystals; Photoinduced effect; Neutral ionic transition; XRD; Bragg reflection; Experimental study; Pulsed lasers; Time resolved spectra; Symmetry breaking; Ferroelectric transitions; Self organization; Laser radiation; Chloranil; Charge transfer complexes; Dimerization; Synchrotron radiation; Organic compounds
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1082001

We report the direct observation by x-ray diffraction of a photoinduced paraelectric-to-ferroelectric structural phase transition using monochromatic 100-picosecond synchrotron pulses. It occurs in tetrathiafulvalene-p-chloranil, a charge-transfer molecular material in which electronic and structural changes are strongly coupled. An optical 300-femtosecond laser pulse switches the material from a neutral to an ionic state on a 500-picosecond time scale and, by virtue of intrinsic cooperativity, generates self-organized long-range structural order. The x-ray data indicate a macroscopic ferroelectric reorganization after the laser irradiation. Refinement of the structures before and after laser irradiation indicates structural changes at the molecular level.