Turning metals into insulators using a new quantum switch

Scientists from the University of British Columbia have recently demonstrated a whole new way to precisely control electrical currents by leveraging the interaction between an electron’s spin, and it’s orbital rotation around the nucleus. They have discovered a new way to switch the electrical conduction in materials from on to off.

The study offers a detailed comprehension of how electrical conduction works. Furthermore, it will help in exploring known properties such as conductivity, magnetism, and superconductivity, and discover new ones that could be important for quantum computing, data storage, and energy applications.

Extensively, all materials can be sorted as metals or insulators, contingent upon the capacity of electrons to travel through the content and conduct electricity.

However, all insulators are different. In simple materials, the difference between metallic and insulating behavior stems from the number of electrons present: an odd number for metals, and an even number for insulators.

On the other hand, in Mott insulators, electrons interactions occur differently with a delicate balance determining their electrical conduction. The electrostatic repulsion in the Mott insulator prevents the electrons from getting too close to one another, which creates a traffic jam and limits the free flow of electrons.

Until now, there were two known ways to free up the traffic jam: by reducing the strength of the repulsive interaction between electrons, or by changing the number of electrons.

Scientists, in this study, explored the third possibility: was there a way to alter the very quantum nature of the material to enable a metal-insulator transition to occur?

They used a technique called angle-resolved photoemission spectroscopy to examine the Mott insulator Sr2IrO4, monitoring the number of electrons, their electrostatic repulsion, and finally, the interaction between the electron spin and its orbital rotation.