Abstract by Richard Hardy
Chemistry and Biochemistry
Understanding and Optimizing Models of Ultrafast Polarization Reversal in Ferroelectric LiNbO3
Utilizing terahertz radiation to coherently reverse the ferroelectric polarization of a material on extremely short timescales has the potential to create ultrafast switches that could increase computing speeds by several orders of magnitude. Key to realizing these applications with any material is gaining a robust understanding of the material's interatomic potential energy surface, so as to design effective excitation pathways to polarization reversal. Here we present first-principles calculations of the interatomic potential energy surface of the ferroelectric oxide LiNbO3, and model the dynamic response following strong terahertz excitation of crystal phonon modes. By considering the coupling of all phonon modes relevant to polarization reversal, we are able to demonstrate the transient polarization reversal observed in recent experiments, and also provide guidance for future experimental attempts to achieve stable polarization reversal.