Liquid Crystals Beyond Displays: Chemistry, Physics, and Applications

Chapter 3

Magnetic Liquid Crystals

Rui Tamura, Yoshiaki Uchida, and Katsuaki Suzuki

Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan

3.1 Introduction

Paramagnetic liquid crystals (PLCs) have been considered to become novel advanced soft materials that can combine the optical and electrical properties of conventional liquid crystals (LCs) with the magnetic and electronic properties of paramagnetic compounds [1–3]. The PLCs are classified into two categories: the majority were metal-containing LCs (metallomesogens) with permanent spins originating from transition (d-block) or lanthanide (f-block) metal ions in the mesogen core [3, 4], while only a few all-organic radical liquid-crystalline (LC) materials were prepared, most likely due to the difficulty in the molecular design and synthesis which must satisfy the molecular linearity or planarity necessary for the existence of LC phases (rod-like or disk-like molecules, respectively) as well as the radical stabilization [1, 5–7]. Moreover, endowing the PLCs with chirality is expected to result in the emergence of unconventional magneto-electric [8–10] or magneto-optical [11–13] properties, intriguing magnetic interactions and so on in the chiral LC state.

Thus, the research on chiral and achiral PLCs is being explored in the context of the following objectives or expectations:

1. Realization of the paramagnetic anisotropy (Δχ_para)-controlled molecular orientation in the chiral and achiral LC phases ...