Russian scientists have synthesized a new material that exhibits the properties of spin liquid, an extremely rare phase of matter that arises in frustrated quantum magnets at low temperatures. Such materials could be used in quantum technologies based on the entanglement of the wave functions of individual particles. The study was published in the Journal of Inorganic Chemistry.
Spin, the intrinsic angular momentum associated with the electron, is a universal property of elementary particles. Many materials have disordered and moving particle spins at room temperature and only freeze and become organized as the temperature decreases.
Quantum spin liquids are materials that display no magnetic order, even at the lowest temperatures. Scientists have speculated their existence since the dawn of quantum mechanics but have only recently begun to search for such material.
The mineral Herbertsmitite has copper ions as carriers of the magnetic moment that form a perfect two-dimensional kagomé lattices (kagomé is the pattern of Japanese wicker ware with a hexagonal motif). Until now, it has been considered as a prime candidate for the realization of quantum spin liquid. Now Russian scientists have added another substance to the list of materials potentially possessing spin liquid properties.
Researchers from Lomonosov Moscow State University and NUST MISIS have synthesized a new sodium bismuth oxo-cuprate phosphate chloride with a square-kagomé-type lattice which exhibits no magnetic ordering or spin freezing when cooled to −271°C. The researchers have therefore hypothesized that the material’s spin subsystems exhibit spin liquid -like behavior at low temperatures.
“Two main periodic fragment modules can be distinguished in the crystal structure of the spin liquid candidate. The first one is the layers formed by clusters of four tetrahedrons. There are oxygen atoms in the centre of each tetrahedron. Three vertices of the tetrahedron have copper atoms and the fourth has a bismuth atom. Such layers carry a positive charge and are ready to share it with the second, negatively charged fragment,” said Alexander Vasiliev, one of the authors of the research, Head of the Functional Quantum Materials Laboratory at NUST MISIS.
According to Prof. Vasiliev, the second layer is combined of polyhedrons containing sodium, phosphorus and copper atoms in the centres and oxygen and/or chlorine atoms in the vertices.
“The nature of the described layers can be viewed as a ’host—guest’ model. Curiously enough, the new compound was obtained with an excess of cooking salt! The salt contributed to the formation of the matrix — the ’host’ that welcomed the ’guest’ fragment of the composition to form a material with unique physical characteristics,” Alexander Vasiliev explained.
He further added that the material could find future applications in quantum technologies based on the entanglement of the wave functions of individual particles.