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Magnetic phenomena in cobalt intermetallides at high pressures

Presented by Mr. Anton RUTKAUSKAS
Type: Oral
Track: Condensed Matter Physics

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Studies of intermetallic compounds based on cobalt are one of the topical problems of condensed matter physics. Such phenomena as magnetism of collectivized electrons, giant magnetoresistance, magnetocaloric effects (MCE), as well as magnetoelastic lattice collapse are found in them. That makes these compounds promising materials for magnetic refrigerators, permanent magnets, etc. In this paper we present the results of the investigation of the compounds RCo2 (where R is Ho, Er, Dy) and YCo4Si by neutron diffraction at high pressures. These studies can provide additional information on the magnetic behavior of cobalt in ordered phases. It is found that in the compounds RCo2 (where R is Ho, Er, Dy) at normal pressure, as the temperature is lowered, a ferrimagnetic phase appears. In the HoCo2 and DyCo2 compounds, the Curie temperature for the rare-earth (Ho and Dy) and cobalt sublattices shift synchronously to the low-temperature region under pressure. In the ErCo2, the Curie temperature splits for erbium and cobalt sublattices under pressure. The Curie temperature for the cobalt lattice shifts to lower temperatures, while for erbium the Curie temperature remains unchanged. This experimental result requires the expansion of the metamagnetism model. In YCo4Si, the ferromagnetic phase is found at normal pressure and low temperatures. There are two non-equivalent positions of cobalt atoms in this compound. It leads to different values of their magnetic moment and the Curie temperature. The Curie temperature for both cobalt atoms shifts to the low temperature region with different baric coefficient under pressure. This work was supported by the Russian Foundation for Basic Research (project no. 17-02-00112)

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