On May 5 local time, a team of chemists and physicists from Columbia University published a paper on nature materials, introducing that there is a close relationship between electron transmission and magnetism in a material called crsbr (full name: chromium sulfide bromide).
Created in the laboratory of chemist Xavier Roy, crsbr is a van der Waals crystal that can be stripped into stackable two-dimensional layers as thin as a few atoms. Unlike those related materials that are quickly destroyed by oxygen and water, crsbr crystals are stable under environmental conditions. These crystals can also maintain their magnetism at a relatively high temperature of - 280f and avoid the need for expensive liquid helium cooled to - 450F.
"Crsbr is much easier than other two-dimensional magnets, which allows us to make novel devices and test their characteristics," said Evan Telford, a postdoctoral fellow at Roy laboratory It is reported that Telford graduated from Columbia University with a doctor of physics in 2020. Last year, his colleagues Nathan Wilson and Xiaodong Xu at the University of Washington and Xiaoyang Zhu at Columbia University found a link between magnetism and crsbr's response to light. In the current research work, Telford led the efforts to explore its electronic characteristics.
The research team used an electric field to study crsbr layers at different electron densities, magnetic fields and temperatures - different parameters can be adjusted to produce different effects in the material. With the change of the electronic characteristics of crsbr, its magnetism is also changing.
"Semiconductors have adjustable electronic properties. Magnets have adjustable spin configurations. In crsbr, the two knobs are combined," Roy said. "This makes crsbr attractive for basic research and potential spintronic applications."
Telford said that magnetism is a property that is difficult to measure directly, especially when the size of the material is reduced, but it is very easy to measure how electrons move with a parameter called resistance. In crsbr, resistance can be used as a proxy for other unobservable magnetic states. "This is very powerful, especially when researchers look forward to one day making chips with this two-dimensional magnet, which can be used for quantum computing and store a large amount of data in a small space," Roy said.
The link between the electronic and magnetic properties of the material is caused by defects in the layer, which Telford said was a lucky breakthrough for the team. "People usually want the 'cleanest' material possible. Our crystals have defects, but without these defects, we wouldn't have observed this coupling."
Right now, Roy lab is experimenting with how to create peelable van der Waals crystals with intentional defects to improve the ability to fine tune material properties. They are also exploring whether different combinations of elements can work at higher temperatures while still retaining valuable combination characteristics.