Features of magnetic and thermal properties of R(Co1−xFex)2 (х≤0.16) quasibinary compounds with R=Dy, Ho, Er

• Magnetic and magnetocaloric properties of R(Co–Fe)2 compounds have been studied.
• Fe introduction induces the disorientation effect in Ho-ions magnetic ordering.
• Emergence of magnetic contribution to a heat capacity at temperatures less TC.
• The existence of a broad maximum on a temperature dependence of the MCE.
• Direct MCE measurements at magnetic field of (0–17.5) kOe have been performed.

In this work the results of measurements of high field susceptibility, paraprocess susceptibility and thermal properties of R(Co1−хFeх)2 intermetallic compounds (R=Dy, Ho, Er and x=(0−0.16)) are presented (heat capacity and magnetocaloric effect (MCE)). A magnetic structure of the Ho(Co0.88Fe0.12)2 at 293 K and 78 K was studied by neutron powder diffraction. Some peculiarities of a high-field susceptibility were revealed at low temperatures and around the Curie point (TC). In temperature range lower than TC by (100–150) K, magnetic contributions to a zero-field heat capacity were found. Studying MCE in wide temperatures range, the large change of the entropy magnetic contribution (∆S) was observed which correlates with ∆T phenomenon. In particular, for the Er(Co0.84Fe0.16)2 compound the ∆S value at low temperatures is six times higher than that at Curie point. The possible reasons of such behavior were discussed.