New artificial materials pave the way for the electronics industry to progress

In the April 10 issue of Nature, a newly published artificial material marks the beginning of a revolution in material development for electronic applications.

This achievement is the result of a collaboration between the theory group of Professor Philippe Ghosez (University of Liège, Belgium) and the experimental group of Professor Jean-Marc Triscone (University of Geneva, Switzerland). One of the leading researchers of the project - Matthew Dawber recently joined Stony Brook University's Department of Astrophysics and Physics - will continue his efforts to research and create artificial materials of personality. network in his laboratory.

The new material, 'super net', has a multi-layered structure consisting of thin atomic layers rotating alternately with two types of oxide (PbTiO3 and SrTiO3) possessing completely different properties from both types of oxide. part. This new feature is a direct result of artificial stratification and is created by interaction at the atomic ratio at the interface of the layers.

Dr. Dawber said: 'Besides the immediate applications of this nanomaterial, the discovery also opens up a completely new field of investigation as well as the potential of new functional materials based on the concept: thorough articulation at atomic scale '.

The atomic scale structure of a 'super network' 1/1 PbTiO3 / SrTiO3 (calculated according to principle 1), gray Pb atoms, blue Sr atoms, green atoms at Ti and O atom is red. The combined electron clouds are yellow. The specific rotation period of the oxygen atom (red) in successive layers is stimulated by artificial placement in the structure; It is also a feature of the non-main electric iron operation discovered. (Photo: University of Liège)

Transitional metal oxides are a group of interesting materials due to their wide variety of properties (they can be dielectric, electric iron, piezoelectric, magnet or superconductor) as well as their ability to combine. in many types of devices. Most of these oxides have similar structure (perovskite material group) and recently, researchers have developed an ability to combine these materials together, layer by atom like a child. Play Lego puzzles, hoping to create new materials with unusual properties.

Electric iron is a group of the most useful materials used in a variety of devices from stable high-end computer memory, to micro-mechanical machines or infrared detectors.'Non-main electric iron' is a type of ferroelectricity that is rarely available in natural materials, its efficiency is often too weak to be applicable. The temperature-dependent property of non-main ferroelectricity is quite different from that of conventional iron. That means they have a lot of great advantages suitable for many applications when the temperature changes. If the iron properties of this material group are stronger, its application will be much more.

This new super-network material is characterized by non-main electric iron (properties that do not exist in component materials) about 100 times greater than conventional iron and iron materials . It promises to open a new door to practical applications worldwide.

PbTiO3 and SrTiO3 are the two most common and typical oxides, which both exhibit unstable properties in the structure of electric iron and exhibit the polarity unstable structure. A theoretical study conducted in Liege (using the first complex rules of quantum mechanical simulation techniques called ab initio quantum method) predicts that when these oxides combine Super network structure, unusual and completely unexpected combination between these two types of unstable materials creates non-main electric iron properties.

Parallel experimental research conducted in Geneva confirmed the non-ferrous superstructure structure , and provided evidence of an unusual but very useful novel property: dielectric constant ( a value indicating the reaction of the material to the electric field) at the same time of great value and independent of temperature, the two types of oxides that seem to be mutually exclusive combine to form a homogeneous material. .

But the reality of this discovery is more important than the immediate applications. The study confirmed the ability to create completely different materials by conducting the technique at the atomic scale, the PbTiO3 / SrTiO3 super net system is just one first example. The idea of ​​combining unstable materials at the interface in artificial multi-layered structures can also be applied to other types of oxides, and is a particularly interesting strategy in the field of multiferroic oxides. develope. The results were obtained after the discovery last year that the interface between two different oxides actually has superconductivity, while no oxide has this property.

This discovery, coupled with current advances, has led Science to classify multistage oxide discoveries into the 2007 group of 10 groundbreaking scientific innovations. Similar to the importance of mastering characteristics. the semiconductor's interface in the development of modern electronics, the creation of new properties at the interface between oxides can bring about a major technological revolution in the years to come. .

References and funding: This study is the result of a group of scientists, Nanosized Ferroelectric Hybrids, the Swiss National Science Foundation (through the National MaNEP Research Center ), European Community (FAME-EMMI and MaCoMuFi).Eric Bousquet (ULg), Matthew Dawber (SBU / UniGe), Nicolas Stucki (UniGe), Céline Lichtensteiger (UniGe), Patrick Hermet (ULg), Stefano Gariglio (UniGe), Jean-Marc Triscone (UniGe) & Philippe Ghosez (ULg) ).Nature 10 April 2008;452 (7188) 732-736.

Previous article: N. Reyren et al., Science 317, 1196 (2007).