New theory explains magnetic trends in high-temperature superconductors

Science (2022). DOI: 10.1126/science.abm2295″ width=”673″ height=”426″/>

(a) Illustration of the multiple fragmentation scheme in the multilayer cuprate Hg-1212. The system is divided into 3 parts: fragments 1 and 2 contain the two Cu-O layers and fragment 3 contains all other ions in the cell. (b) MPI efficiency of the multifragment implementation of an h-BN crystal. Recognition: Science (2022). DOI: 10.1126/science.abm2295

In almost every situation that uses electricity, whether it’s lighting a bedroom at night, keeping frozen food cold, or powering a car that takes a commuter to work, some of that electrical energy is lost as heat. That’s called resistance. Materials with lower resistance conduct electricity better, materials with higher resistance worse.

Although almost all conductors have some resistance, there are some materials that have no electrical resistance at all. These are known as superconductors, and their unique properties are used in technologies ranging from magnetic resonance imaging (MRI) to levitated trains.

However, most superconductors are only superconductive when they are cold—really cold. Even so-called “high-temperature” superconductors have to be cooled to around -200 degrees Celsius with liquid nitrogen in order to function.

This need for intensive cooling adds a major complication to the use of superconductors. For decades, researchers have been looking for superconductors that work at room temperature. Currently, at normal atmospheric pressure, the class of high-temperature superconductors known as cuprates – compounds containing both copper and oxygen atoms – comes closest, with the highest-performing cuprate being able to function at temperatures as “warm” as – 140 degrees Celsius to superconductor.

Since -140 degrees Celsius is still quite cold, there is still a long way to go before cuprates can be called room temperature superconductors, and further development of these superconductors has been hampered by the fact that no one has figured out how cuprate superconductors work .

But now researchers in Garnet Chan’s group, Caltech’s Bren professor of chemistry, have developed a theory that explains some of the magnetic properties of cuprate superconductors. Cuprate superconducting materials exhibit a layer effect in which their magnetic and superconducting properties are enhanced as more layers of the constituent copper and oxygen atoms are brought together.

In an article published in the magazine ScienceChan and his co-authors explain how the magnetic layer effect arises from fluctuations in the electrons between the copper and oxygen atoms and their surrounding atoms.

“This is a first step in understanding the rationale behind the superconducting layer effect and what more generally controls the superconducting temperature in superconductors,” says Zhihao Cui, a PhD student in chemistry and first author of the study.

The publication is entitled “Systematic electronic structure in the cuprate parent state from quantum many-body simulations” and appears in the September 8 issue Science.

More information:
Zhi-Hao Cui et al, Systematic electronic structure in the cuprate parent state from quantum many-body simulations, Science (2022). DOI: 10.1126/science.abm2295

Provided by the California Institute of Technology

Citation: New Theory Explains Magnetic Trends in High-Temperature Superconductors (2022, December 1), retrieved December 1, 2022 from .html

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