Engineering the Magnetocaloric Effect in Nd$T_4$B

TL;DR

This study investigates the magnetocaloric effect in Nd$T_4$B compounds with tunable magnetic properties, engineering compositions to maximize MCE and exploring their potential for wide-temperature-range cooling applications.

Contribution

The paper presents a comprehensive characterization and engineering of Nd$T_4$B compounds to optimize the magnetocaloric effect across a broad temperature range.

Findings

Nd$T_4$B compounds exhibit a wide temperature range of notable entropy change.

Engineered composition NdFe$_{1.15}$Co$_{0.46}$Ni$_{2.39}$B shows maximized MCE.

Presence of two-peak MCE in some compositions suggests potential for multi-stage cooling.

Abstract

We present a comprehensive study of the magnetocaloric effect (MCE) in the Nd$T_4$B system where $T$ = Fe, Co, and Ni. These compounds are ferromagnetic kagome materials with tunable ordering temperatures, transition width, and magnetic moments depending on the choice of transition metal. Thus, they are good candidates for investigating the MCE. We characterize the MCE using standard metrics and construct ternary phase diagrams as functions of Fe, Co, and Ni concentrations. Using these phase diagrams, we engineer the composition NdFe$_{1.15}$Co$_{0.46}$Ni$_{2.39}$B to maximize the MCE. Interestingly, the Nd$T_4$B system shows a notable entropy change over a wide temperature range ($\sim$10 to 650 K), and particular compositions have notable MCEs spanning hundreds of Kelvin, making this a suitable system to study for technologies used in a wide range of temperatures. In a few cases, we observe a two-peak MCE. These two transitions, releasing comparable entropy, provide an interesting platform to study for applications in multi-stage cooling.