Atomic 'Swiss Army knife' precisely measures quantum materials

July 07, 2020 //By Rich Pell
Atomic 'Swiss Army knife' precisely measures quantum materials
Scientists at the National Institute of Standards and Technology (NIST) say they have developed a novel instrument that can make three kinds of atom-scale measurements simultaneously.

Designed to to study quantum materials, the instrument images single atoms, maps atomic-scale "hills and valleys" on metal and insulating surfaces, and records the flow of current across atom-thin materials subject to giant magnetic fields. Together, say the researchers, these measurements can uncover new knowledge about a wide range of special materials that are crucial for developing the next generation of quantum computers, communications, and a host of other applications.

For example, the instrument could be used to measure properties such as the resistance-less flow of electric current, quantum jumps in electrical resistance that could serve as novel electrical switches, and new methods to design quantum bits, which could lead to solid-state-based quantum computers. In a paper on the device, the researchers present a detailed recipe for building the instrument, which they describe as "a kind of Swiss Army knife for atom-scale measurements."

"We describe a blueprint for other people to copy," says NIST researcher Joseph Stroscio. "They can modify the instruments they have; they don't have to buy new equipment."

The instrument combines a trio of precision measuring devices. Two of the devices - an atomic force microscope (AFM) and a scanning tunneling microscope (STM) - examine microscopic properties of solids, while the third tool records the macroscopic property of magnetic transport — the flow of current in the presence of a magnetic field.

"No single type of measurement provides all the answers for understanding quantum materials," says NIST researcher Nikolai Zhitenev. "This device, with multiple measuring tools, provides a more comprehensive picture of these materials."

To build the instrument, the researchers designed an AFM and a magnetic-transport-measuring device that were more compact and had fewer moving parts than previous versions. They then integrated the tools with an existing STM.

Both an STM and an AFM use a needle-sharp tip to examine the atomic-scale structure of surfaces. An STM maps the topography of metal surfaces by placing the tip

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