Observation of Griffiths-like phase and magnetocaloric effect in disordered Y2CoCrO6 double perovskite

Abstract

The increasing demand for advanced materials with multifunctional magnetic properties has sparked growing interest in rare-earth and transition metal-based double perovskites. In this study, we comprehensively investigate disordered Y₂CoCrO₆ (YCCO), synthesized via the sol–gel method. Structural analysis confirms a single-phase orthorhombic crystal structure with B-site disorder, as revealed by X-ray photoelectron spectroscopy, which also identifies mixed valence states of Co and Cr due to antisite disorder and oxygen vacancies. This structural disorder profoundly impacts YCCO′s magnetic properties, leading to the emergence of a Griffiths-like phase, detected through inverse susceptibility measurements. Additionally, the material exhibits both antiferromagnetic and weak ferromagnetic behaviors, evidenced by a negative Curie–Weiss temperature and unsaturated magnetic hysteresis loops. Arrott plot analysis indicates a second-order phase transition and magnetocaloric measurements reveal a maximum entropy change (S_max) of 0.217 J kg⁻¹ K⁻¹, a relative cooling power (RCP) of 17.36 J kg⁻¹, and a temperature averaged entropy change (TEC) of 0.17 J kg⁻¹ K⁻¹ over a temperature span (T_lift) of 30 K under a 5 T field, showcasing its potential for low-temperature and multistage cooling applications. Although its modest magnetocaloric effect (MCE) performance is attributed to its antiferromagnetic nature with weak ferromagnetic contributions and a low Curie temperature, this work represents a significant step in unveiling the potential of YCCO for multifunctional applications. Future optimization through chemical doping, nanostructuring, and compositional modifications is proposed to enhance its magnetocaloric and functional properties, positioning YCCO as a strong candidate for advanced magnetic and cooling technologies.