The material that passes from metal to insulation

The material that passes from metal to insulation

Scientists develop lanthanum nickellate sheets capable of changing property depending on their thickness

   A metal is capable of conducting electricity while an insulator is not, or at least we thought until now. A group of researchers from Cornell University and the Brookhaven National Laboratory (United States) have shown how to transform the properties of a metal oxide, lanthanum nickel (LaNiO3) into an insulator, simply by making layers of this material less than one nanometer thick. This discovery is published in the latest issue of Nature Nanotechnology.

The size of electronic devices could be reduced much more with the help of these transition metal oxides, a class of materials with spectacular properties, such as superconductivity or magnetoresistance.

The researchers used an extremely precise growth technique called molecular beam epitaxy (MBE) whereby Phil King, the first author of the study, synthesized an atomically thin samples of lanthanum nickel and discovered that the material changed abruptly. from metal to insulator when its thickness was reduced below 1 nanometer.

Upon crossing that threshold, its conductivity, that is, the ability of the electrons to flow through the material, was quenched. This feature could be useful in the construction of nanoscale switches or transistors, as noted by principal investigator Kyle Shen of Cornell University.

King and his companions studied the movements and interactions of the electrons in the material, and how they changed by varying the thickness of the lanthanum nickel-to-atom lanthanum plates. They discovered that when the films had less than 3 nickel-thick atoms, the electrons formed an unusual order, similar to a chessboard, but on a nanoscale.

The results show that it is possible to control the electronic properties of transition metal oxides in the nanometer scale, as well as reveal the surprising interactions that govern the behavior of electrons in these ultra-fine materials. These discoveries pave the way for the manufacture of new advanced electronic devices.