Magnetic properties and large low-field magnetocaloric effect of RFe2Si2 (R = Ho, Tm) compounds.

• RFe 2 Si 2 (R = Ho, Tm) intermetallic compounds were successfully synthesized. • Ultra-low working temperature and large low-field magnetocaloric effect were obtained. • Good thermal and magnetic reversibility were confirmed based on the analysis of transition. • RFe 2 Si 2 (R = Ho, Tm) compounds show potential applications on low-temperature magnetic cooling. Nowadays, magnetic refrigerant technology has drawn much attention for its environmental friendliness. Those magnetic materials possessing giant low-field magnetocaloric effect (MCE) performance are of great importance for practical applications, especially at low temperatures. Herein, we present a detailed study on polycrystalline magnetocaloric compounds HoFe 2 Si 2 and TmFe 2 Si 2. HoFe 2 Si 2 exhibits a transition from antiferromagnetic to paramagnetic phase at 2.2 K, while no long-range magnetic ordering is observed in TmFe 2 Si 2 even temperature down to 2 K. For both compounds, they showed large low-field magnetic entropy change (−ΔS M) with the peak values of 10.6 and 7.9 J kg−1 K−1 under field change of 0–2 T for HoFe 2 Si 2 and TmFe 2 Si 2 , respectively, which is comparable or even larger than some low-temperature magnetocaloric materials. In addition, the characteristic of second-order magnetic transitions of both compounds were confirmed on basis of Arrott plots and mean-field theory criterion. The low magnetic ordering temperatures, large low-field MCE performance along with the feature of second order phase transition for HoFe 2 Si 2 and TmFe 2 Si 2 indicate that both compounds are promising candidate for magnetic refrigerant materials at liquid helium temperature. [ABSTRACT FROM AUTHOR]