Delving into manganite conductivity

Chemical compounds called manganites have been studied for many years since the discovery of colossal magnetoresistance, a property that promises important applications in the fields of magnetic sensors, magnetic random access memories and spintronic devices.

On the left, is a picture of the structure of LaMnO3. On the right, is a diagram of how the Jahn-Teller effect distorts the structure of LaMnO3.

However, understanding - and ultimately controlling - this effect remains a challenge, because much about manganite physics is still not known. A research team lead by Maria Baldini from Stanford University and Carnegie Geophysical Laboratory scientists Viktor Struzhkin and Alexander Goncharov has made an important breakthrough in our understanding of the mysterious ways manganites respond when subjected to intense pressure.

At ambient conditions, manganites have insulating properties, meaning they do not conduct electric charges.

When pressure of about 340,000 atmospheres is applied, these compounds change from an insulating state to a metallic state, which easily conducts charges. Scientists have long debated about the trigger for this change in conductivity.

The research team's new evidence, to be published online by Physical Review Letters on Friday, shows that for the manganite LaMnO3, this insulator-to-metal transition is strongly linked to a phenomenon called the Jahn-Teller effect.