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Jonas Fischer
Electronic Ferroelectricity in Organic Charge-Transfer Salts
Supervisor: Prof. Dr. Alois Loidl [Experimental physics V]
Date of oral examination: 09/11/2018
129 pages, english , ISBN:9783843937924
The novel phenomenon of electronic ferroelectricity enables the development of high-speed electronic devices and provides a new approach to find members of the rare class of multiferroics. These materials, which exhibit both polar and magnetic order, facilitate the development of next-generation devices and reduce the energy consumption of existing ones. In this work, dielectric spectroscopy, polarization, and positive-up-negative-down measurements were employed to cast light on the dipolar interactions and the origins of polar order in four organic charge-transfer salts. All compounds exhibit different mechanisms of generating electronic ferroelectricity: intra-dimer charge order, a mixed-stack arrangement combined with dimerization, and charge order in a one-dimensional crystal. The organic charge-transfer salts had previously been known for their strong electronic correlations and diverse physical properties. By contributing to the understanding of the driving mechanisms of electronic ferroelectricity and multiferroicity, this work helps in establishing a new path toward environmentally friendly and efficient devices.