Memristors (memory + resistors) have been hyped as leading the future of computers but the problem has been that no one really knew how they worked - until now.
HP, which discovered memristors in 2008, teamed with scientists from the University of California at Santa Barbara to study them and discovered how current flow caused heating that changed the molecular structure of the device. They also discovered that memristors function like the neurons that pass information around the human brain. See HP figures out how memristors work, predicts robot use by ZDNet UK's David Meyer.
Memristors are a "thin titanium dioxide film held between two metal electrodes, and they act within circuitry as resistors. However, memristors have the added quality of remembering the resistance they had when current last flowed through them, hence the portmanteau name. Their resistance increases or decreases depending on the direction of the current," according to ZDNet UK's David Meyer.
"Representing a fourth basic passive circuit element, memristors have the ability to ‘remember’ the total electrical charge that passes through them," says Research associate John Paul
Electrical charge flowing through a memristor changes the resistance state of the device, but actually observing the corresponding material changes has been a challenge. Highly focused x-rays were used to probe the memristor non-destructively and a ~100 nm region with concentrated oxygen vacancies (right, shown in blue) where the memristive switching occurs was discovered. Surrounding this region a newly developed structural phase (red) was also found, which acted like a thermometer telling researchers where and how hot it became.
Caption credit: HP
"One of the biggest hurdles in using these devices is understanding how they work: the microscopic picture for how they undergo such tremendous and reversible change in resistance. We now have a direct picture for the thermal profile that is highly localised around this channel during electrical operation, and is likely to play a large role in accelerating the physics driving the memristive behavior." - John Paul Strachan of the nanoElectronics Research Group at HP Labs.
The timeline of memristors.