Giant and highly anisotropic magnetocaloric effects in single crystals of disordered-perovskite RCr0.5Fe0.5O3 (R = Gd, Er)
Hyun Jun Shin, Jin seok Kim, Ki Won Jeong, Jong Hyuk Kim, Nara Lee, Young Jai Choi
Abstract
Abstract Magnetic anisotropy is crucial in examining suitable materials for magnetic functionalities because it affects their magnetic characteristics. In this study, disordered-perovskite RCr 0.5 Fe 0.5 O 3 (R = Gd, Er) single crystals were synthesized and the influence of magnetic anisotropy and additional ordering of rare-earth moments on cryogenic magnetocaloric properties was investigated. Both GdCr 0.5 Fe 0.5 O 3 (GCFO) and ErCr 0.5 Fe 0.5 O 3 (ECFO) crystallize in an orthorhombic Pbnm structure with randomly distributed Cr 3+ and Fe 3+ ions. In GCFO, the long-range order of Gd 3+ moments emerges at a temperature of T Gd (the ordering temperature of Gd 3+ moments) = 12 K. The relatively isotropic nature of large Gd 3+ moment originating from zero orbital angular momentum exhibits giant and virtually isotropic magnetocaloric effect (MCE), with a maximum magnetic entropy change of $$\Delta {S}_{M}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>S</mml:mi> <mml:mi>M</mml:mi> </mml:msub> </mml:mrow> </mml:math> ≈ 50.0 J/kg·K. In ECFO, the highly anisotropic magnetizations result in a large rotating MCE characterized by a rotating magnetic entropy change $$\Delta {S}_{\theta }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>S</mml:mi> <mml:mi>θ</mml:mi> </mml:msub> </mml:mrow> </mml:math> = 20.8 J/kg·K. These results indicate that a detailed understanding of magnetically anisotropic characteristics is the key for exploring improved functional properties in disordered perovskite oxides.