Unexpected quantum behavior in insulators

A TEAM LED BY PRINCETON PHYSICISTS DISCOVERED A SURPRISING QUANTUM PHENOMENON IN AN ATOMICALLY THIN INSULATOR MADE OF TUNGSTEN DITELLURIDE. THE RESULTS SUGGEST THE FORMATION OF COMPLETELY NEW TYPES OF QUANTUM PHASES PREVIOUSLY HIDDEN IN INSULATORS. CREDIT: IMAGE DESIGNED BY KAI FU FOR THE WU LAB, PRINCETON UNIVERSITY

Physicists at Princeton University have observed an unexpected quantum behavior in an insulator made from a material called tungsten ditelluride. This phenomenon, known as quantum oscillation, is typically observed in metals rather than insulators, and its discovery offers new insights into our understanding of the quantum world.

The observation of quantum oscillations has long been considered a hallmark of the difference between metals and insulators. In metals, electrons are highly mobile, and resistivity — the resistance to electrical conduction — is weak.

Nearly a century ago, researchers observed that a magnetic field, coupled with very low temperatures, can cause electrons to shift from a “classical” state to a quantum state, causing oscillations in the metal’s resistivity. In insulators, by contrast, electrons cannot move and the materials have very high resistivity, so quantum oscillations of this sort are not expected to occur, no matter the strength of magnetic field applied.

The researchers then set about measuring the resistivity of the monolayer tungsten ditelluride under magnetic fields. To their surprise, the resistivity of the insulator, despite being quite large, began to oscillate as the magnetic field was increased, indicating the shift into a quantum state. In effect, the material — a very strong insulator — was exhibiting the most remarkable quantum property of a metal.

No current theories explain this phenomenon so the findings hint at the existence of an entirely new type of quantum particle. (SciTechDaily)

The work has been published in Nature.

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