New magnetic materials based on RNi compounds for cryogenic technology

Magnetocaloric properties of Gd(Ni$_{0.98}$Si$_{0.02}$) and Dy(Ni$_{0.95}$Si$_{0.05}$) compounds and their hydrides Gd(Ni$_{0.98}$Si$_{0.02}$)H$_{3}$ and Dy(Ni$_{0.95}$Si$_{0.05}$)H$_{4}$ have been studied in a temperature interval of 2–100 K. It is established that the partial substitution of Si atoms for Ni atoms and subsequent hydrogenation can lead to significant changes in the Curie temperature, magnitude of the magnetocaloric effect, and temperature at which this effect is at maximum. In the hydrides, the characteristic temperatures shift to lower values by several dozen degrees while the magnetocaloric effect increases or remains the same, which can significantly expand the application of these materials in cryogenic technology.