Effect of off-stoichiometry and Ta doping on Fe-rich (Mn,Fe)&lt;sub&gt;2&lt;/sub&gt;(P,Si) based giant magnetocaloric materials

Zhang, F.; Batashev, I.; van Dijk, N.H.; Brück, E.H.

doi:10.1016/j.scriptamat.2022.115253

Effect of off-stoichiometry and Ta doping on Fe-rich (Mn,Fe)₂(P,Si) based giant magnetocaloric materials

Title

Effect of off-stoichiometry and Ta doping on Fe-rich (Mn,Fe)₂(P,Si) based giant magnetocaloric materials

Author

Zhang, F. (TU Delft RST/Fundamental Aspects of Materials and Energy)
Batashev, I. (TU Delft RST/Fundamental Aspects of Materials and Energy; Radboud Universiteit Nijmegen)
van Dijk, N.H. (TU Delft RST/Fundamental Aspects of Materials and Energy)
Brück, E.H. (TU Delft RST/Fundamental Aspects of Materials and Energy)

Date

2023

Abstract

The influence of off-stoichiometry and of doping with the 5d transition metal Ta has been studied in the quaternary (Mn,Fe)₂(P,Si)-based compound, which is one of the most promising materials systems for magnetic refrigeration. It is found that Ta substitution can decrease the transition temperature T_tr, while the thermal hysteresis ∆T_hys remains about constant. A low Ta doping enhances the magnetocaloric effect (MCE). For Mn_0.6Fe_1.27-_yTa_yP_0.64Si_0.36 with y = 0.01 the magnetic entropy change ∆S_m shows and enhancement of 30.7% compared to the undoped material for a low magnetic field change of 1 T. The occupancy of substitutional Ta atoms is determined by XRD and DFT calculations. The T_tr shift and enhanced MCE upon Ta doping are ascribed to the competition between a weakening of the magnetic exchange interactions and a strengthening of the hybridization. Our studies provide a good strategy to further optimize the MCE of this material family.