A One Hundred Year Perspective of the Reentrant Nematic Phase.

Since the discovery of liquid crystals one hundred years ago, reentrant phase transitions have transformed from being isolated curiosities to an established phenomenon. A significant influence for this change in point of view has been the almost overnight discovery of many reentrant transitions in liquid crystals. In this review, I survey some of the interesting results discovered by different groups studying the reentrant nematic phase since its discovery making contact with current theories whenever possible. To put the reentrant nematic in the context of current understanding and to provide a historicals perspective of this phenomenon, I summarize some reentrant transitions in other systems. In particular, I discuss the ferroelectric transition in the molecular crystal, Rochelle salt, because it may be the first observed example of a reentrant. Again, whenever possible, similarities and differences to the liquid crystal case are discussed.