This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A team of Yale researchers has figured out what gives a magnetic material its mysterious properties, a discovery that could help boost computing memory and the field of "spintronics." Their work is published in Physical Review Letters. Iron-intercalated niobium disulfide (FeₓNbS₂) is a material in which iron atoms are inserted into the gaps between layers of niobium disulfide.
Materials scientists have taken a great interest in the material because they can switch its resistance states by sending electrical current pulses through it. "This is a very surprising thing, because usually it's difficult to switch such states with electrical current at a low density," said professor Yu He, who led the study. Wenxin Li, a Ph.D. student in He's lab, is the first author.
This ability to change its resistance states in such a way makes the material promising for spintronics, in which the spin of electrons is used to store or manipulate information. That could potentially boost computing memory while using significantly less energy. Further, it could help advance quantum and neuromorphic computing, among other benefits.
Exactly what gives this material such interesting properties, though, has been a mystery. While researchers knew that this material could easily switch magnetic states, it wasn't clear why. Previously, researchers in the field used a technology known as X-ray scattering to study the magnetic orderings.
However, mobile electrons in metallic magnets like FeₓNbS₂ can dampen the signals and make the magnetic interaction strengths difficult to determine. To crack the mystery, Li used a technology known as angle-resolved photoemission spectroscopy (ARPES) to get a close look at the electrons' activity, which fundamentally determines both the electrical and magnetic properties. This provides a complementary way to investigate the electronic interactions that mediate magnetism.
What the team found was that the ratio of iron to niobium disulfide was critical to how the electrons from each material interacted with each other. When the material is composed of one-third iron, narrow iron-derived electronic states mix strongly with niobium-derived states, a process known as hybridization. Above an iron concentration of one-third, the iron-derived states lose coherence and, along with it, their ability to hybridize with niobium.
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