Third Harmonic Generation and χ(5) Effects in Thin Gradient HfO2 LayersDavid Zuber, Sven Kleinert, Ayhan Tajalli, Morten Steinecke, Marco Jupé, Ihar Babushkin, Detlev Ristau and Uwe MorgnerEPJ Web Conf., 267 (2022) 01043DOI: https://doi.org/10.1051/epjconf/202226701043