Enhancement of magnetocaloric effect in all-d-metal Heusler Mn52.6Ni30.5Co7.8Ti9.1/PVA/PET flexible composite by mechanical strains

Abstract

The prominent enhancement of magnetocaloric effect (MCE) and the extension of effective magnetic refrigeration temperature region near room temperature (RT) are urgent needs for efficient and clean refrigeration technologies. Here, we report that a flexible composite is made up of all-d-metal Heusler ferromagnetic shape memory alloys (FSMAs) Mn52.6Ni30.5Co7.8Ti9.1 (Mn-Ni-Co-Ti) ribbon and polyethylene terephthalate (PET) substrate with polyvinyl alcohol (PVA) coating, exhibiting a tunable martensitic transformation (MT) by applying mechanical strains and accompanying a remarkably enhanced MCE near RT. The MT temperature of the Mn-Ni-Co-Ti/PVA/PET flexible composite obviously shifts, leading to the bidirectional control of the magnetization difference (ΔM) with the increase of tensile/compressive strains. Especially, the magnetic entropy change (ΔSM) and refrigeration capacity (RC) are remarkably improved under the tensile strain (ε = 6.0%) state. As a result, the MCE can be controlled and the effective magnetic refrigeration temperature region can be expanded by adjusting the mechanical strains in the Mn-Ni-Co-Ti/PVA/PET flexible composite, which is beneficial to improve the refrigerating efficiency in promising applications of magnetic devices.