Logic test: Arrays of memristors located where these electrical contacts converge can perform logic and memory functions.
A Memory and Logic Device
HP researchers demonstrate logic with memristors
Source: “ ’Memristive’ switches enable ‘stateful’ logic operations via material implication”
R. Stanley Williams et al.
Nature 464: 873-876
Results: Researchers at Hewlett-Packard have shown that nanoscale circuit elements called memristors, which have previously been made into memory devices, can perform full Boolean logic, the type used for computation in computer processors.
Why it matters: Memristor logic devices are about an order of magnitude smaller than devices made from transistors, so they could pack more computing power into a given space. Memristor arrays that perform both logic and memory functions could eliminate the need to transfer data between a processor and a hard drive in future computers, which would save energy.
Methods: HP researchers fabricated memristors of various sizes on a silicon substrate by growing metal nanowires, coating them with titanium dioxide, and topping them with another series of metal nanowires oriented perpendicular to the first group. A memristor is formed where the two layers of wires cross. Each wire was connected to some test circuitry that the researchers used to bring current into the system. Using this test system, the researchers showed that a pair of memristors could serve as a logic gate: it processed information by switching one of the memristors on or off to create a 1 or a 0, depending on the initial states of the two elements. The memristors could also serve as a “latches”–that is, they retained data, “remembering” whether they had recently switched to a 1 or a 0.
Next steps: The basic material properties of the metal oxides used to make memristors are still not well understood, so it’s not clear whether the devices will be as reliable as silicon transistors. HP Labs researchers are working toward introducing a memory product based on memristors in 2013, and researchers will learn more as they develop facilities to make them.