Recent observations of ferroelectricity in mixed hafnia and zirconia thin films have been surprising, since the bulk crystal phases of the individual materials are non-polar in the absence of applied electric fields. The ferroelec- tricity can be traced back to a metastable, polar orthorhombic phase, which however is nearly indistinguishable from the tetragonal phase in grazing incidence X-ray diffraction. This indicates that better tools for optical characterization and identification of thin film crystalline phases are needed. Here we describe a first-principles methodology for obtaining a collection of optical properties such as the dielectric and electro-optical tensors, as well as infrared and Raman spectra. We illustrate how these can be used to guide material characterization of thin film dielectrics, by identifying distinct fingerprint signatures for each phase, which potentially can be used for real-space identification and characterization of ferroelectric regions.
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