(July 1, 2015) DVDs and Blu-ray disks contain so-called phase-change materials that morph from one atomic state to another after being struck with pulses of laser light, with data "recorded" in those two atomic states. Using ultrafast laser pulses that speed up the data recording process, Caltech researchers adopted a novel technique, ultrafast electron crystallography (UEC), to visualize directly in four dimensions the changing atomic configurations of the materials undergoing the phase changes. In doing so, they discovered a previously unknown intermediate atomic state—one that may represent an unavoidable limit to data recording speeds.
By shedding light on the fundamental physical processes involved in data storage, the work may lead to better, faster computer memory systems with larger storage capacity. The research, done in the laboratory of Ahmed Zewail, Linus Pauling Professor of Chemistry and professor of physics, will be published in the July 28 print issue of the journal ACS Nano.
When the laser light interacts with a phase-change material, its atomic structure changes from an ordered crystalline arrangement to a more disordered, or amorphous, configuration. These two states represent 0s and 1s of digital data.