Magnetic coupling between Gd and Pr ions and magnetocaloric effect in Gd0.5Pr0.5Al2 compound

Abstract

a b s t r a c tIn this work, we report the theoretical and experimental investigations on the magnetic and magnetocaloric properties for Gd 0.5 Pr 0.5 Al 2 compound in different magnetic fields. The magnetization features indicate that Gd 0.5 Pr 0.5 Al 2 is ferrimagnetic at low temperatures. We also present data from X-ray magnetic circular dichroism (XMCD) experiments for this compound, with which we have confirmed that the magnetic moments of the Pr ions are antiparallel to the magnetic moments of the Gd ions. The magnetocaloric parameters, DT S and DS T , were obtained from calorimetric data and both curves present normal and inverse magnetocaloric effect. A theoretical model for ferrimagnetic coupling, including the crystalline electrical field anisotropy, was used to describe the DT S and DS T experimental results.

Magnetic and Magnetocaloric Properties of (Gd1-xCex)Al2(x = 0, 0.25, 0.5, 0.75) Compounds

“…The measured value of the Curie temperature for GdAl 2 (x = 0) is approximately in agreement with literature values reported in Refs. [27][28][29]. It is clearly seen that Ce substitution slightly decreases the Curie temperatures of the samples.…”

“…In RE 1-x RE' x Al 2 (where RE and RE' = rare earth elements) type alloys, the nature of the magnetic ordering and the Curie temperature are strongly dependent on the intersublattice exchange interactions, and therefore on the spin-orbit couplings [32] between rare-earth elements. In many previous studies it has been reported that in systems in which either both rare-earth elements are light (from Ce to Sm) or both are heavy (from Gd to Yb), the resulting exchange coupling is ferromagnetic, whereas for lightheavy combinations the exchange coupling is ferrimagnetic [15,29,35]. Recent experimental and theoretical works have confirmed the existence of ferrimagnetic coupling in Gd 1-x Pr x Al 2 alloys [15,29].…”

“…In many previous studies it has been reported that in systems in which either both rare-earth elements are light (from Ce to Sm) or both are heavy (from Gd to Yb), the resulting exchange coupling is ferromagnetic, whereas for lightheavy combinations the exchange coupling is ferrimagnetic [15,29,35]. Recent experimental and theoretical works have confirmed the existence of ferrimagnetic coupling in Gd 1-x Pr x Al 2 alloys [15,29]. In Gd 1-x Ce x Al 2 compounds, due to the light-heavy combination of Ce and Gd atoms, the resulting exchange interaction between Gd-Ce is expected to be ferrimagnetic.…”

“…2) in the low temperature range. The Lande g factor was taken from [29] directly. The estimated parameters are listed in Table 1.…”

“…These recent studies have showed that the ground state for most intermetallic Laves compounds is ferromagnetic. Among these materials, GdAl 2 is ferromagnetic with a Curie temperature between 153 and 182 K [28,29]. Jianqiu et al [27] have reported that the maximum magnetic entropy change of GdAl 2 is 4 J/kg K for a magnetic field of 2 T and the Curie temperature is 165 K. Despite the fact that its Curie temperature is relatively low compared to room temperature, GdAl 2 shows a relatively large MCE.…”