Successive magnetic transitions and low temperature magnetocaloric effect in RE2Ni7 (RE=Dy, Ho)

Magnetic properties of rare-earth intermetallics RE2Ni7 (RE=Dy, Ho) are reported. Both the samples undergo two successive magnetic transitions at Th (paramagnetic to ferromagnetic) and Tl (spin reorientation) below 100 K. The transitions are found to be second order in nature as evident from the Arrot plot analysis. Large reversible magnetocaloric effect (MCE) was observed at low temperature in the studied samples. The maximum value of the magnetic entropy change in Ho2Ni7 is found to be −12.5 J/kg K (for 0 to 50 kOe of field change) around 25 K with a high relative cooling power (RCP) of 534 J/kg. The Dy counterpart also shows moderately large values of MCE (−7.3 J/kg K) and RCP (475 J/kg) around the magnetic transition region for similar change in the magnetic field. RE2Ni7 compounds can be promising materials for magnetic refrigeration in the temperature range of helium and hydrogen liquefaction.

Research Highlights
► Multiple magnetic anomalies with low temperature spin reorientation transition.
► Large low temperature reversible magnetocaloric effect.
► High value of relative cooling power suitable for magnetic refrigeration