Jlich/Aachen, 3 May 2011 - Optical data carriers such as DVDs, Blu-rays and CD-RWs store data in layers of so-called "phase change materials". In the future, these materials will enable the development of fast, non-volatile and energy-saving main memories. A prerequisite for this is a low thermal conductivity. Phase change materials display a surprisingly low thermal conductivity even in the crystalline state. This is described by an international research team including scientists from Jlich and Aachen in the latest edition of the respected journal Advanced Functional Materials (DOI: 10.1002/adfm.201002274). Their findings will facilitate a targeted search for materials with the desired properties.
Phase change materials are among the favourite candidates for developing a "universal memory", which is as fast as DRAM (dynamic RAM), has high storage density, is always ready for use and does not lose data even when inadvertently turned off. The data is stored in tiny areas of different electrical resistance, which are written to by heating with the aid of electric pulses. In doing so, the atomic ordering of the material and its electrical resistance is changed.
When heated, phase change materials switch from the unordered (amorphous) to the ordered (crystalline) state, which leads to a change in their physical properties. This feature has been exploited by industry for many years in optical data carriers such as DVDs, Blu-rays and CD-RWs. By means of a laser, the atomic structure and thus the optical properties are changed in minute areas of the discs. This allows bits to be written to the disc and be read out again by a laser.
"In order to produce energy-saving and tightly packed electronic memories, it is important when the data are written to the disc that the electrical resistance is significantly changed but that the energy remains as localized as possible," explains Dr. Raphal Hermann from the Jlich Centre for Neutron Scie
|Contact: Angela Wenzik|
Helmholtz Association of German Research Centres