Unique quantum materials could enable ultra-powerful compact computers

In computers, information is transmitted through semiconductors by the movement of electrons and is stored in the direction of electron spin in magnetic materials. To shrink devices while improving their performance – a goal of an emerging field called spintronics (“spintronics”) – researchers are looking for unique materials that combine quantum properties. Writing in Nature Materials, a team of chemists and physicists at Columbia University have found a strong link between electron transport and magnetism in a material called chromium sulfide bromide (CrSBr).

Created in the lab of chemist Xavier Roy, CrSBr is a so-called van der Waals crystal that can be peeled back into stackable 2D layers that are just a few atoms thin. In contrast to related materials that are rapidly destroyed by oxygen and water, CrSBr crystals are stable at ambient conditions. These crystals also maintain magnetic properties at a relatively high temperature of -280 F, obviating the need for expensive liquid helium cooled to -450 F,

Colleagues Nathan Wilson and Xiaodong Xu at the University of Washington and Xiaoyang Zhou in Columbia said Evan Telford, a postdoctoral researcher in Roy’s lab who received a Ph.D. in physics from Columbia in 2020. found a link Between magnetism and how CrSBr responds to light. In the present work, Telford has led efforts to explore it Electronic properties.

The team used a file electric field To study CrSBr layers across different electron densities, magnetic fields, and temperatures — different parameters can be modified to produce different effects in a material. As the electronic properties of CrSBr changed, so did its magnetism.

“Semiconductors have tunable electronic properties. Magnets have tunable spin configurations. In CrSBr, these two handles are combined,” Roy said. “This makes CrSBr attractive to both basic research and for potential spintronics applications. “

Telford explained that magnetism is a property that is difficult to measure directly, especially as the size of a material shrinks, but it is easy to measure how electrons move with a parameter called resistance. In CrSBr, the resistance can act as a proxy for unobservable magnetic states. “This is very powerful,” Roy said, especially as researchers look to one day build chips of 2D magnets that can be used in Quantitative Statistics And to store huge amounts of data in a small space.

Telford said the link between the material’s electronic and magnetic properties was due to imperfections in the layers — for the team, he was lucky. “People usually want the cleanest material possible,” he said. “Our crystals have flaws, but without them, we wouldn’t have noticed this pairing.”

From here, Roy’s lab is testing ways to grow peelable van der Waals crystals with intentional defects, to improve the ability to fine-tune the material’s properties. They are also exploring whether different combinations of elements can function at higher temperatures while retaining these valuable aggregate properties.