Magnetic and magnetocaloric properties of Gd6(Mn1−xCox)23 compounds (x ≤ 0.3)

Abstract

The magnetic and magnetocaloric properties of the Th6Mn23-type structure Gd6(Mn1−xCox)23 (x ≤ 0.3) compounds are investigated from DC magnetization measurements. The Curie temperature of these ferrimagnetic materials evolves non-continuously with the Co content from TC = 489 K for x = 0 to TC = 118 K for x = 0.3. In relation with the lower magnetic moment of Co atoms compared with that of Mn atoms, the Co to Mn substitution leads to a decrease of the maximal magnetization, recorded at 5 K in an applied magnetic field of 9 T, from 54.7 μB/f.u. for x = 0 to 36.3 μB/f.u. for x = 0.3. These materials present an anomalous magnetocaloric effect, characterized by two broad –ΔSM maxima of moderate magnitude at TC and around 100 K, yielding to wide magnetocaloric response from TC down to the lowest temperature, and consequently, a relatively large cooling capacity q10–350K (μ0ΔH = 5 T) reaching ∼ 3.7 J cm−3 for Gd6(Mn0.875Co0.125)23. The results are analyzed and discussed in connection with previously published data.