Unveiling the structure–magnetism interplay in the ferrimagnetic pyrochlore Gd2CrSbO7 with significant cryo–magnetocaloric performance

Abstract

Magnetic refrigeration is a promising and efficient cooling technology that uses the magnetocaloric effect (MCE), requiring particular materials with low heat capacity, low ordering temperature, and large magnetic moments for high performance. Here we report on Gd2CrSbO7, a mixed B-site pyrochlore oxide that exhibits a significant cryogenic MCE, driven by intricate 4f-3 d exchange interactions. Our combined experimental and theoretical investigation reveals that Gd2CrSbO7 crystallizes in a cubic pyrochlore structure (Fd3m) with ferrimagnetic (FiM) ordering, uniquely hosting a Griffiths-like phase and a Schottky anomaly arising from competing Cr-Cr short-range interactions and Gd crystal field effects. X-ray Raman spectroscopy confirms super-exchange interactions, while EXAFS analysis identifies enhanced Sb-O bond rigidity, influencing the material's stability. Notably, Gd2CrSbO7 achieves a remarkable maximum magnetic entropy change of -Delta SMmax\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$-\Delta {S}_{M}<^>{\max}$$\end{document} approximate to 21 J/kg K and refrigerant capacity of RC approximate to 430 J/kg (at 0-7 T), comparable to benchmark cryogenic refrigerants like Gd3Ga5O12, but containing substantially low-priced elements. These findings position Gd2CrSbO7 as a promising platform for next-generation magnetic cooling, while shedding light on emergent magnetic and electronic phenomena in pyrochlore oxides.