**Yoichi Takanishi**

Department of Physics, Graduate School of Scince, Kyoto University, Kitashirakawaoiwake, Sakyo, Kyoto 606-8502, Japan; ytakanis@scphys.kyoto-u.ac.jp

Received: 30 September 2020; Accepted: 17 November 2020; Published: 19 November 2020

**Abstract:** The study of chiral symmetry breaking in liquid crystals and the consequent emergence of ferroelectric and antiferroelectric phases is described. Furthermore, we show that the frustration between two phases induces a variety of structural phases called subphases and that resonant X-ray scattering is a powerful tool for the structural analysis of these complicated subphases. Finally, we discuss the future prospects for clarifying the origin of such successive phase transition.

**Keywords:** chirality; symmetry breaking; ferroelectricity; antiferrolelectricity; subphases; resonant X-ray scattering
