Generating Metal Oxides Using Epitaxial Strain Allows the Creation of Quantum Materials With Atomic Precision

Stubborn metal oxides play a significant role in quantum information sciences and electronics. The oxides of metals in the platinum group are very valuable in future electronics and spintronics. This is due to the interaction of spin-orbit combinations and electron correlation energies.

However, these metals are difficult to convert to thin films, posing a challenge for researchers brought by the innate troubles in oxidizing them with high-vacuum processes. Fabricating these stubborn metals has baffled scientists for decades. Although some experts achieved oxidation successfully, their methods were expensive, unsafe, and resulted in poor-quality materials.

Giving It a Stretch

It is now possible to create high-quality thin films made of metal oxide from stubborn metals which were previously difficult to synthesize in the past atomically. This was proven by a team of scientists composed of chemical engineering and materials science researchers from the University of Minnesota Twin Cities.

Initially, the researchers attempted to synthesize metal oxides using typical molecular beam epitaxy. This low-energy strategy creates single layers of materials in an ultra-high vacuum chamber. However, they found a groundbreaking discovery when epitaxial strain stretches the stubborn metals effectively at the atomic level. This finding can simplify the oxidation process of these metal oxides.

The team used iridium and ruthenium as their study subjects, but they revealed that their discovered strategy could generate oxides using hard-to-oxidize metals. Researchers hope their groundbreaking discovery will enable scientists to synthesize novel materials more effectively. The outcome of this research could also pave the way for developing better materials with various applications in quantum computing, energy catalysis, and microelectronics.

According to lead author Sreejith Nair, "The current synthesis approaches have limits, and we need to find new ways to push those limits further so that we can make better quality materials. Our new method of stretching the material at the atomic scale is one way to improve the performance of the current technology."

Understanding Metal Oxidation

All metals tend to oxidize when exposed to oxygen or an electrolyte. This chemical reaction happens at the surface of the metal as the oxygen in the air corrodes the metal and forms oxide. In the initial oxidation stage, a supply of atomic oxygen is required in addition to adequate mobility of metal atoms on its surface.

Metal oxidation is also frequently associated with unwanted corrosion of materials, especially those we use daily. If oxidation is carried out under controlled conditions, it can help produce beneficial substances and materials such as catalysts, semiconductors, and useful oxide films.

In chemical engineering processes, iridium and ruthenium are the most significant metals. Iridium is the top metal that can resist corrosion, and certain molten salts cannot easily attack it. On the other hand, ruthenium is used as a hardener for other metals like palladium and platinum and can significantly improve the corrosion resistance of some elements like titanium.