The second-order magnetic phase transition and magnetocaloric effect in all-d-metal NiCoMnTi-based Heusler alloys

Zhang, F.; Westra, Kevin; Shen, Q.; Batashev, I.; Kiecana, A.; van Dijk, N.H.; Brück, E.H.

doi:10.1016/j.jallcom.2022.164337

The second-order magnetic phase transition and magnetocaloric effect in all-d-metal NiCoMnTi-based Heusler alloys

Title

The second-order magnetic phase transition and magnetocaloric effect in all-d-metal NiCoMnTi-based Heusler alloys

Author

Zhang, F. (TU Delft RST/Fundamental Aspects of Materials and Energy)
Westra, Kevin (Student TU Delft)
Shen, Q. (TU Delft RST/Fundamental Aspects of Materials and Energy)
Batashev, I. (TU Delft RST/Fundamental Aspects of Materials and Energy)
Kiecana, A. (TU Delft RST/Fundamental Aspects of Materials and Energy)
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

2022

Abstract

The novel all-d-metal Ni(Co)MnTi based magnetic Heusler alloys provide an adjustable giant magnetocaloric effect and good mechanical properties. We report that the second-order magnetic phase transition can be tailored in this all-d-metal NiCoMnTi based Heusler system by optimizing the Mn/Ti ratio, resulting in a reversible ferromagnetic-to-paramagnetic magnetic transition. A candidate material Ni₃₃Co₁₇Mn₃₀Ti₂₀ with a magnetic entropy change ∆S_m of 2.3 Jkg⁻¹K⁻¹ for a magnetic field change of 0–5 T, has been identified. The T_C and saturation magnetization M_S can be controlled by adjusting the Ni/Co concentration and doping non-magnetic Cu atoms. The compositional maps of T_C and M_S have been established. Density functional theory (DFT) calculations reveal a direct correlation between the magnetic moments and the Co content. By combining XRD, SQUID, SEM and DFT calculations, the (micro)structural and magnetocaloric properties have been investigated systematically. This study provides a detailed insight in the magnetic phase transition for this all-d-metal Ni(Co)MnTi-based Heusler alloy system.