Scientists knew that switching process was taking place but found it hard to study because memristors are so tiny. HP's latest breakthrough was to use highly focused X-rays to pinpoint a channel, just 100 nanometers wide, where the resistance switching takes place. A nanometer is about a millionth of a centimeter.
They then mapped out the chemistry and structure of that channel, and thus gained a better idea of how memristors operate. The paper was jointly published by HP and UC Santa Barbara.
The type of memory that can be built with memristors, called ReRAM, is nonvolatile, which means devices can retain their data after the power supply is turned off. That's in contrast to DRAM, where the stored data is lost when the power is cut.
Williams estimated that HP's memristor technology could be commercially available by the middle of 2013, though "that's not an official promise from HP as a company," he said.
HP has built sample devices in its labs that should enable storage densities of 12G bytes per square centimeter, Williams said That's using a 15-nanometer production process and a multi-level design, where four layers of memory cell are stacked on top of one another.