Giant magnetocaloric effect in an exchange-frustrated GdCrTiO5 antiferromagnet

Abstract

We report the effect of exchange frustration on the magnetocaloric properties of GdCrTiO5 compound. Due to the highly exchange-frustrated nature of magnetic interaction, in GdCrTiO5, the long-range antiferromagnetic ordering occurs at much lower temperature TN =0.9 K and the magnetic cooling power enhances dramatically relative to that observed in several geometrically frustrated systems. Below 5 K, isothermal magnetic entropy change (-∆Sm) is found to be 36 J kg −1 K −1 , for a field change (∆H) of 7 T. Further, -∆Sm does not decrease from its maximum value with decreasing in T down to very low temperatures and is reversible in nature. The adiabatic temperature change, ∆T ad , is 15 K for ∆H=7 T. These magnetocaloric parameters are significantly larger than that reported for several potential magnetic refrigerants, even for small and moderate field changes. The present study not only suggests that GdCrTiO5 could be considered as a potential magnetic refrigerant at cryogenic temperatures but also promotes further studies on the role of exchange frustration on magnetocaloric effect. In contrast, only the role of geometrical frustration on magnetocaloric effect has been previously reported theoretically and experimentally investigated on very few systems. arXiv:1805.02056v1 [cond-mat.mtrl-sci]

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Magnetoelastic Coupling and Cryogenic Magnetocaloric Effect in Two-Site Disordered GdSrCoFeO6 Double Perovskite

“…We also observed that the frustration factor, defined as f frus = |Θ Weiss |/ T C , yields f frus = 0.65, 0.78, and 0.75, respectively. Theses values are less than 1 and indicate that the system is not geometrically frustrated. − The observed paramagnetic moments ( p eff ) are 11.1, 10.4, and 10.2 μ B /f.u. for the three fields mentioned (50 Oe, 500 Oe, and 5 kOe).…”

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“…A few contain precious Rh (e.g., FeRh [24,222,278,279] and Tb 3 Rh [270]). Many contain critical rare earth, such as Eu in Eu 2 In [140], EuTiO 3 [114,135,156,195] doped with Al [113], Cr [196], Mn [134], Co [151], Ni [119], Ba [157,206], Nb [110,170,195] and Eu in other compounds [133,232,240,251]; Gd in GdAlO 3 [158], GdFeO 3 [138,162], GdCrO 3 [183], GdCrO 4 -ErCrO 4 [202], GdScO 3 [117,124], Gd 2 CoMnO 6 [155], Gd 2 BaNiO 5 [152], GdCrTiO 5 [143], GdCo 2 B 2 [271], GdCoC 2 [171], RuSr 2 GdCu 2 O 8 [208], etc. ; Tb in TbFeO 3 [176], TbMn 2 O 5 [179], Tb 2 CoMnO 6 [132], Tb 5 Ge 2−x Si 2−x Mn 2x [255], Tb 4 Gd 1 Si 2.035 Ge 1.935 Mn 0.03 [197], etc.…”