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In previous studies, we have reported that double perovskiteLa NiMnO (LNMO) presents a non-negligible potential for room temperature magnetocaloric tasks. With the aim of improving even further the cooling performances and the working temperature range of double perovskites, we report the magnetic and magnetocaloric properties of La MnFeO and related compounds. The partial substitution of strontium for lanthanum enables us to cover a wide operating temperature range with significant magnetic entropy change extending beyond 300 K. For some optimal growth conditions, the entropy change varies slowly over an unusually large temperature range, which is of clear interest from a practical point of view.

The influence of the W-doping on the martensitic transformation, magnetic properties and exchange bias (EB) effect in the Ni47Mn40Sn13-xWx (x=0, 0.5, 1, 1.25 at.%) magnetic shape memory alloys has been investigated. It is found that the W-doping causes a simultaneous reduction ofboth the ferromagnetic exchange coupling and enhancement of the magnetic anisotropy, leading to a decrease of the magnetic moment of the low-temperature phase and to a higher attainable EB. The magnetic memory measurements reveal the presence of a glassy magnetic ground state, which can significantly impact the reduction of magnetization and enhancement of EB in the studied bulk alloys. It is argued that the glassy magnetic ground state originates from the partial magnetic disorder resulting from the correlation between the antiferromagnetic and ferromagnetic states. The results demonstrate that the doping by W instead of Sn is an efficient tool to tailor the EB effect in the Ni-Mn-Sn-based Heusler alloys, whereby they are promising for spintronic applications.

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