Magnesium oxide and a wide array of other materials have been studied as potential substrates for growing magnetic thin films. In the photomicrograph above, nickel oxide molecules are shown on a substrate of magnesium oxide, but the materials do not appear to be a very good match since the nickel oxide is raised in many small islands, rather than flat, smooth, and flawless. Despite the disappointment of incompatibility between certain materials, scientists are getting increasingly closer to creating a selection of practical thin films that could be used for a variety of applications. One of the most exciting developments has been the successful and progressive work on magnetic tunnel junctions, which consist of a thin insulating film sandwiched between two magnetic thin films. Though still being fine-tuned, magnetic tunnel junctions may eventually be able to replace semiconductor equipment now used for a computer's random access memory (RAM). If and when this change in computer technology comes to pass, then power interruptions will no longer mean a loss of data held in RAM, since magnetic tunnel junctions operate magnetically rather than electrically.