Nonvolatile memories (NVMs) are key devices in computers to save a user’s information. Besides flash memory, several types of NVMs that use magnetoresistance, resistance change of metal oxides, and phase change of chalcogenide alloys have been studied. Among these, phase-change random-access memory (PC-RAM) is competitive from the viewpoint of switching speed, high durability, and scalability. In 2017, Intel and Micron Technology shipped commercial devices named Optane that use a phase-change material as storage class memories. Condensed-matter physicists have recently been attracted to phase-change materials because of their functionality as topological insulators. If the topological phase state is controllable and applied to PC-RAM, electron spin transfer and storage effects will be further available in addition to electrical resistance switching.