ReRAM or RRAM (Resistive Random Access Memory) is a non volatile memory being studied by several companies (including Fujitsu, Sharp and Samsung). It has a structure that can exist in two forms with different electrical resistances, representing 0 or 1 in a memory cell. The change from one state to the other is made by applying a certain voltage to the terminals of the resistor (writing). The value of the resistance shows the state of the memory (reading).
Several materials have been tested, including metal oxides (e.g. nickel, titanium) and perovskite (ferroelectric ceramics). Whatever the material, the principle is the same. When writing, with a sufficiently high voltage a structure in the form of a weak electrically resistant filament forms in the substrate. With a higher voltage, this filament breaks, and the electrical resistance increases (by a factor of the order of a hundred).
The ReRAM is proposed as a rival and possible successor to Flash memory, having the advantage of a greater potential for miniaturisation and lower consumption.