https://phys.org/news/2018-11-storage.html

Phase-change materials triggered by electrical impulses—rather than light—would offer new memory technologies with more stable and faster operation than that possible in many current types of memory devices. In addition, downscaling memory sites in phase-change materials could increase memory density. But this remains challenging because of the difficulty of controlling the crystallization and amorphization (melting) processes.

Addressing this issue in an article in Physical Review Letters, a team of scientists led by Kyoto University observed nanometer-scale growth of individual crystals in a phase-change material composed of germanium, antimony and tellurium—or GST—after applying high-powered terahertz pulses as a trigger.