Search

The Nd 2 Pt 2 In compound was investigated by means of electrical resistivity ρ ( T ) , heat capacity C p ( T ) , magnetic susceptibility χ ( T ) , magnetization M ( μ 0 H ) and magnetocaloric effect (MCE) measurements. The material orders ferromagnetically at T C = 16 K with a second - order phase transition. In the ordered state, ρ ( T ) can be represented in terms of ferromagnetic (FM) spin - wave dispersion with an energy gap Δ R = 13(1) K in zero field. In concert, the C p ( T ) data in this region can be well described by the same model getting Δ C = 8(1) K in zero field. Above T C , the ρ ( T ) variation is characteristic of electron - phonon interaction in the presence of s − d scattering and crystalline-electric field (CEF). The 4 f - electron specific heat shows a Schottky - type anomaly around 60 K associated with CEF. On the other hand, C p ( T ) data of the non-magnetic homologue La 2 Pt 2 In can be described by the Debye - Einstein model, giving a Debye and Einstein temperature values of 190.3(5) K and 69.8(7) K respectively. At high temperatures, the χ ( T ) data follows the Curie - Weiss relation with an effective magnetic moment μ e f f = 3.61(2) μ B and a Weiss temperature θ p = 17(1) K. The magnitude of MCE was estimated from the isothermal magnetization data to be 6.25 J/(kg.K), 5.01 J/(kg.K), 3.18 J/(kg.K) and 0.47 J/(kg.K) for a field change of 7 T, 5 T, 3 T and 1 T, respectively. The characteristic behaviour of the isothermal magnetic entropy change points to a second - order character of the FM phase transition.

The magnetic ordering in Pr 2 Pt 2 In was investigated by means of magnetization and magnetic susceptibility measurements. The compound was found to order ferromagnetically at T C = 8.8(2) K with a second-order phase transition. The derived critical exponents β = 0.325(2), γ = 1.058(2) and δ = 4.26(4) are close to those expected for a 3D Ising ferromagnet.

Critical behavior in the Nd2Pt2In compound around the ferromagnetic phase transition at TC was investigated based on the magnetocaloric effect (MCE). The critical exponent values β = 0.42(6), γ = 1.25(2) and δ = 4.00(2) obtained from the magnetic entropy change at TC and the critical magnetization isotherm, M(μ0H, TC), indicated that the magnetic interactions in this compound follow two different universality classes below and above TC, which can be described in terms of the 3D-Heisenberg and 3D-Ising models, respectively. The studies by means of the conventional method using different techniques gave values of the critical exponents that are in close agreement with those derived from the MCE analysis and also confirmed two different behaviors in the ferromagnetic and paramagnetic states.

We report on the low-temperature physical properties of RE 8 Pd 24 Ga (RE = Gd, Tb and Dy) compounds studied by means of thermodynamic and electronic transport measurements. The three compounds exhibit a putative antiferromagnetic ordering. In the paramagnetic region, their magnetic susceptibility follows the Curie-Weiss relation with effective magnetic moments close to those expected for the respective RE 3 + ions. Gd 8 Pd 24 Ga and Dy 8 Pd 24 Ga undergo another magnetic phase transitions in the ordered state. In fairly small magnetic fields, the magnetization of Tb 8 Pd 24 Ga and Dy 8 Pd 24 Ga reveals a metamagnetic-like transition that bears a first-order character. All three compounds studied exhibit magnetocaloric effect of the magnitude similar to those reported for materials applicable as magnetic refrigerants.