Insight into the structural and magnetic properties of RECo12B6 (RE = Ce, Pr, Nd) compounds: A combined experimental and theoretical investigation

Abstract

Rare earth (RE) based RE-TM-X (TM = transition metal elements; X = P-block elements) materials have received continuous attention due to the exhibition of various intriguing magnetic functional characteristics. In this work, a combined experimental and theoretical investigation has been conducted in detail for RECo12B6 (RE = Ce, Pr, Nd) compounds with regard to their structural and magnetic properties, particularly the magnetocaloric effect and magnetic phase transition (MPT). All of the present RECo12B6 compounds are found to crystalize in the SrNi12B6-type structure and with a ferrimagnetic ground state, which is confirmed by density functional theory calculations and magnetization measurements. The magnetic moments of RE atoms and Co atoms tend to be in antiparallel alignment, and the MPT of these materials originates primarily from the spin-polarized 3d electrons of the Co atoms, which can be greatly affected by the 4f electrons of RE atoms. Considerable magnetocaloric effects have been observed around its own TC of 130, 157, and 160 K, for CeCo12B6, PrCo12B6, and NdCo12B6, respectively, which is related to a typical second-order MPT. The corresponding maximum magnetic entropy change and relative cooling power values,with field changes of 0–70 kOe, are determined to be 2.54, 2.84, and 2.77 J/kg K and 116.8, 156.2, and 155.1 J/kg, respectively. The MPT properties of present RECo12B6 compounds were studied in further detail by critical analysis using the modified Arrott Plot and Kouvel-Fisher methods, which can be explained within the frame of the 3D Heisenberg model with short-range magnetic interaction.