Solid State Quantum Electronics - What are we doing? And why?

 

Most materials found in nature are oxides, which are crystals of oxygen and at least one other material bound together with regular spacing. A few common examples are glass (silicon and oxygen), rust (iron and oxygen), and porcelain (aluminum, silicon, oxygen, and water). A branch of these materials called complex oxides feature some truly amazing properties such as superconductivity, which is the ability to transport electricity long distances with no loss of power (like a perfect power cable) at much higher temperatures than anything discovered so far, although much lower than the freezing temperature of water.

 

What makes complex oxides so special is the huge variety of ways that oxygen and other atoms can be assembled together and the tendency of the electrons orbiting the atoms to interact with each other, meaning that the electrons may act as a group instead of individually. These properties are not present in everyday metals such as steel or the silicon used to run today’s computers.

 

 

In our department we are particularly interested in combining different complex oxide crystals at the atomic scale because sometimes the contact area where two different crystals are joined have more interesting properties than the crystals themselves. One example of this is the combination of strontium titanate and lanthanum aluminate. Under the right conditions, a very thin layer of lanthanum aluminate grown onto strontium titanate can have superconducting properties where the two crystals meet, even though the crystals themselves are insulators like the protective plastic housings around electrical cables.

 

 

To study these complex oxides, we use cutting-edge equipment to grow layers of these crystals with accuracies down to a single layer of atoms, which is between 10,000 and 100,000 times thinner than a human hair. Our focus is to study such materials both to better understand the world around us on an atomic level and to find materials that could be used in the next generation of electronic chips, batteries, and power-conducting components within the coming 20 years.