Critical behavior and magnetocaloric effect of Gd65Mn35−xGex (x = 0, 5, and 10) melt-spun ribbons

Abstract

Gd65Mn35−xGex (x = 0, 5, 10) alloy ribbons were prepared by melt-spinning. A fully amorphous structure was obtained for the alloys with x = 5 and 10, whereas, in melt-spun Gd65Mn35 ribbons, crystalline phases (α-Gd and GdMn2) precipitate in the amorphous matrix. The magnetic phase transition from ferromagnetic to paramagnetic is second order. The critical exponents are deduced from the Kouvel-Fisher method and scaling behavior. The obtained critical exponents are in agreement with the theoretical values of 3D Ising model. The Ising-like behavior suggests the presence of large anisotropy and short-range magnetic-coupling behavior. The maximum magnetic-entropy changes of the melt-spun alloys with x = 0, 5, and 10 for a magnetic field change from 0 to 5 T are 4.2, 4.1, and 4.5 Jkg−1 K−1, respectively. All three alloys have a broad temperature range of the magnetic-entropy peak, resulting in large refrigerant capacities.

Thermochemical properties and glass forming tendency modeling for the ternary Ge–Mn–Gd melts

“…The isolines of the obtained B  S / k values for the ternary Ge-Mn-Gd system plotted in the concentration triangle are shown in Figure 5 (solid lines). should be noted that the compositions of the amorphous alloys obtained by rapid quenching in [6] fall into the indicated regions (see Figure 4).…”

“…The composition of the compounds (8) and (6) from Figure 3 also fall into the region of easy amorphization, which means that one can expect to obtain these magnetic phases in amorphous state.…”

Critical Behavior near the Ferromagnetic to Paramagnetic Phase Transition in Y8Co62B30 Amorphous Alloy

“…Scaling hypothesis was used for calculations utilizing M (H) curves as the input data. The critical behavior of a second-order transition can be characterized by a set of critical exponents [6,7]. Exponent β is connected with the spontaneous magnetization M sp , γ with the inverse initial magnetic susceptibility χ −1 0 and finally δ with the critical magnetization isotherm at the Curie temperature.…”

Magnetic properties and magnetocaloric effects in GdCo9Si2 compound with multiple magnetic phase transitions

“…2 In a previous work, we have investigated the magnetic properties and magnetocaloric effect of compounds (Gd 12Àx Tb x )Co 7 (x ¼ 0, 4, and 8), 3 amorphous Gd 4 Co 3 alloys, 4 and Gd 65 Mn 35Àx Ge x (x ¼ 0, 5, and 10). 5 All families exhibited large magnetic entropy change (DS M ). However, the high contents of transition metals generally lead to the decrease of saturations because of their ferrimagnetic nature.…”