Giant low field magnetocaloric effect in TmCoSi and TmCuSi compounds

High-efficiency and environment-friendly magnetic refrigeration, as a replacement to conventional gas compression, has drawn increasing attention. In this article, polycrystalline TmCoSi and TmCuSi compounds were successfully synthesized and giant low field magnetocaloric effect (MCE) was investigated. Under field change of 0–1 T, (-ΔSM)max of 12.0 J/kg K and 8.7 J/kg K and (ΔTad)max of 6.2 K and 3.7 K were obtained at low temperatures for TmCoSi and TmCuSi compounds, respectively. It could be considered as one of the best low-temperature MCE materials compared with reported ErMn2Si2 compound showing (-ΔSM)max and (ΔTad)max of 14.7 J/kg K and 2.5 K respectively. Furthermore, a low-field and reversible giant MCE around the boiling point of liquid helium with the negligible thermal and magnetic hysteresis indicates that TmCuSi and TmCoSi compounds could be potential candidates of magnetic refrigeration for liquid helium temperature region. •Giant MCE was obtained in TmCoSi and TmCuSi compounds in low temperature zone.•Giant MCE can be induced by field change as low as 0–1 T.•The nature of second order was confirmed by several methods in TmCoSi and TmCuSi compounds.