Nickelates May Replace Silicon in Electronic Devices
The scientists at University of Geneva have come up with a
silicon replacement in electronic devices that may be made up of very thin
layers of nickelates. This could be exploited to accurately control some of the
material's electronic properties, such as the sudden transition from a
conductive to an insulating state.It could also be used to develop new, more
energy-efficient devices. "Nickelates are known for a special
characteristic: they suddenly switch from an insulating state to that of an
electrical conductor when their temperature rises above a certain
threshold," begins Jean-Marc Triscone, a professor in the Department of
Quantum Matter Physics in UNIGE’s Faculty of Science. "This transition
temperature varies according to the composition of the material."
Nickelates are formed from a nickel oxide with the addition of an atom belonging to so-called rare earth elements (i.e. a set of 17 elements from the Periodic Table). When this rare earth is samarium (Sm), for example, the metal-insulator jump takes place at around 130°C, while if it is neodymium (Nd), the threshold drops to -73°C. This difference is explained by the fact that when Sm is replaced by Nd, the compound’s crystal structure is deformed – and it is this deformation that controls the value of the transition temperature.
In their attempt to learn more about these materials, the Geneva-based scientists studied samples made up of repeated layers of samarium nickelate deposited on layers of neodymium nickelate – a kind of super sandwich where all the atoms are perfectly arranged.