SCIENTIFIC EDUCATIONAL CENTER science idea

Russian scientists have managed to obtain a new material that, when cooled to low temperatures, demonstrates the properties of a spin liquid – a special magnetic state of matter in which the spins of individual atoms do not freeze even at temperatures close to absolute zero.

Materials with the properties of a spin liquid can be used in quantum technologies based on the entanglement of wave functions of individual particles. The work was published in the journal Organic Chemistry.

A universal property of elementary particles is the spin-the intrinsic magnetic moment of an electron. In many materials, at room temperature, the spins are disordered and move, but they freeze (order) they are only with a decrease in temperature. A spin liquid is an extremely rare state of matter in which the electron spins remain disordered and continue to move even at temperatures close to absolute zero.

The possibility of the existence of such a state of matter was considered at the dawn of quantum mechanics, but scientists have started searching for such a material relatively recently. To date, the main candidate for the realization of a spin liquid is the mineral herbertsmithite, in which copper ions, as carriers of the magnetic moment, form an ideal two-dimensional kagome lattice (kagome is a pattern of Japanese wicker dishes with a hexagonal motif). Thanks to the discovery of Russian scientists, another substance has been added to the list of materials that potentially have the properties of a spin liquid.

Researchers from Lomonosov Moscow State University and NUST MISIS synthesized crystals of sodium oxocuprate chloride-phosphate and bismuth with a square kagome-type lattice, in which no magnetic order is formed when cooled to -271°C. In this regard, the researchers assumed that in the material they created at low temperatures, the spin subsystem behaves like an entangled spin liquid.

"The synthesized object consists of atoms of sodium, copper, bismuth, phosphorus, oxygen and chlorine. In the crystal structure of the candidate for spin liquids, two main fragments can be distinguished-modules. The first is the layers formed by clusters of four tetrahedra. Oxygen atoms are located in the center of each tetrahedron. In three vertices of the tetrahedron there are copper atoms, and in the fourth there was a place for a bismuth atom.

Such layers carry a positive charge and are ready to share it with a second, negatively charged fragment. This layer is combined from polyhedra, in the centers of which there are sodium, phosphorus and copper atoms, and oxygen and/or chlorine atoms at the vertices. The relationship of the described layers is often interpreted as a "guest-host" model. Interestingly, the new compound was obtained with an excess of ordinary table salt!

The salt contributed to the formation of the host matrix, which welcomed the "guest" fragment of the composition with the formation of a material with unique physical characteristics, "explains Alexander Vasiliev, one of the authors of the study, head of the laboratory" Functional Quantum Materials " at NUST MISIS.

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