Crystal structure, magnetic properties and magnetocaloric performance of RE$_{5}$Rh$_2$In$_4$ (RE = Gd-Tm) compounds

TL;DR

This study investigates the crystal structure, magnetic properties, and magnetocaloric effects of RE5Rh2In4 compounds (RE = Gd-Tm), revealing their complex magnetic behavior and potential for low-temperature magnetic refrigeration applications.

Contribution

It provides detailed characterization of RE5Rh2In4 compounds, highlighting their magnetic ordering and magnetocaloric performance, and compares them with related isostructural materials.

Findings

Compounds crystallize in orthorhombic structure.

Magnetic ordering occurs at low temperatures (4.9-15.4 K).

Maximum magnetic entropy change varies with RE element, indicating potential for magnetic refrigeration.

Abstract

Polycrystalline samples of the RE$_{5}$Rh$_2$In$_4$ (RE = Gd--Tm) intermetallics have been investigated by means of X-ray diffraction (XRD) as well as by DC and AC magnetometric measurements. The XRD data confirm that the compounds crystallize with the orthorhombic Lu$_{5}$Ni$_2$In$_4$-type structure (space group Pbam, No. 55). With decreasing temperature, RE$_{5}$Rh$_2$In$_4$ spontaneously order magnetically with the critical temperatures of magnetic order equal to 10.6, 14.2, 15.4, 7.2, 5.9 and 4.9 K for RE = Gd, Tb, Dy, Ho, Er and Tm, respectively. The compounds have complex magnetic properties, showing features characteristic of both ferro- and antiferromagnetic orderings. Moreover, the magnetic properties change with increasing number of the 4f electrons from predominantly ferromagnetic in Gd$_{5}$Rh$_2$In$_4$ to predominantly antiferromagnetic in Tm$_{5}$Rh$_2$In$_4$. The magnetic data indicate that only the rare earth atoms carry magnetic moments. The maximum magnetic entropy change ($-\Delta S_{M}^{max}$) at the 0-9 T magnetic flux density change ($\Delta \mu_0 H$) equals 12.4 J$\cdot$kg$^{-1}\cdot$K$^{-1}$ at 17 K for Gd$_{5}$Rh$_2$In$_4$, 11.3 J$\cdot$kg$^{-1}\cdot$K$^{-1}$ at 28 K for Tb$_{5}$Rh$_2$In$_4$, 13.1 J$\cdot$kg$^{-1}\cdot$K$^{-1}$ at 19 K for Dy$_{5}$Rh$_2$In$_4$, 16.4 J$\cdot$kg$^{-1}\cdot$K$^{-1}$ at 12 K for Ho$_{5}$Rh$_2$In$_4$, 15.3 J$\cdot$kg$^{-1}\cdot$K$^{-1}$ at 8 K for Er$_{5}$Rh$_2$In$_4$ and 12.6 J$\cdot$kg$^{-1}\cdot$K$^{-1}$ at 6.5 K for Tm$_{5}$Rh$_2$In$_4$. For a selected rare earth element (RE), the member of the RE$_{5}$Rh$_2$In$_4$ family of compounds reaches the highest $-\Delta S_{M}^{max}$ value, when compared with its RE$_{5}$T$_2$In$_4$ (T = Ni, Pd, Pt) isostructural analogues, making the RE$_{5}$Rh$_2$In$_4$ intermetallics a good choice for application in low-temperature magnetic refrigeration.