Understand the behavior of conductive and magnetic materials,where they interact and interact with other material, is fundamental to the development of various devices that process, store and transfer information.
Devices such as transistors, magnetic memory, and lasers can improve if researchers look more closely at the properties of these compounds, which affect the conductivity of the material and magnetism.
Specifically, this approach examines how the level of covalent and ionic bonds between metal atoms and oxygen changes as they move from one material to another.
This interface can add new functionality to the material stack. But, to investigate firsthand how the properties of electrons at interfaces differ from those of electrons without interfaces, techniques needed by which the properties of individual atomic layers can be spatially solved.
Ionic and covalent bonds are key concepts in materials science that describe how atoms come together to form solid materials. In ionic bonds, electrons transferred from one atom to another.
The attraction between a positively charged ion cation and a negatively charged ion anion pulls atoms together, creating bonds. In contrast, covalent bonds occur when two atoms share electrons, instead of transferring them completely.
However, many materials contain bonds that are best described as a mixture of ionic and covalent compounds. In these materials, the degree to which the bonds are ionic or covalent influences their electronic properties.
In the reflection experiment, the researchers analyzed the X-ray model scattered by the material to understand the relative density of electrons in the material. Reflectance data can be used to determine the concentration of electrons on their distance from the surface of the material.
By adjusting the wavelength of X-rays to stimulate electronic transitions for individual elements in a pile of material, the team can measure the electronic contribution of each element to their shared bonds and show how ionic or covalent they are.
The material used in this study consisted of alternating layers of two transition metal oxides from strontium ferrite and calcium ferrite. These materials are interesting because they have many exotic electronic properties of quantum materials, including the transition from metal to an isolated state after cooling.
With the help of X-ray reflection, the team was able to measure for the first time how the contribution of oxygen and iron to the electronic character layered and at the interface of the two different compounds.
“We surprised that the covalence between materials has changed because the electronic structures of each are very similar,” the researchers said. But, by interacting with the thin films of these two materials, we can balance their physical structure and change the bonding of the atoms, which in turn affects the electronic and magnetic properties.
Understanding how the interface of unusual materials such as quantum materials works can be the first step to using their properties to improve the processing capabilities, storage, and communication of electronic devices.