Compositional Dependence of Curie Temperature and Magnetic Entropy Change in the Amorphous Tb–Co Ribbons

Abstract

The Curie temperature (Tc) and magnetic entropy change (−ΔSm), and their relationship to the alloy composition of Tb–Co metallic glasses, were studied systematically in this paper. It was found that, in contrast to the situation in amorphous Gd–Co ribbons, the dependence of Tc on Tb content and the maximum −ΔSm vs. Tc -2/3 plots in Tb–Co binary amorphous alloys do not follow a linear relationship, both of which are supposed to be closely related to the non-linear compositional dependence of Tb–Co interaction due to the existence of orbital momentum in Tb.

Formability and Magnetic Properties of the Binary Nd-Co Amorphous Alloys

“…the Dy-Co and Tb-Co binary MG systems [8,28], the compositional dependence of Tc in the binary Nd-Co MGs followed a non-linear relationship. The non-linear relationship between the Curie temperature and Co content in the Dy-Co, Tb-Co and Nd-Co binary MGs is supposed to be closely related to the anisotropic 3d-4f interaction between the RE (Tb, Dy and Nd)-Co atoms.…”

“…The higher the Tc was, the larger the Hc at 10 K became. The high coercivity obstructed the magnetization of the samples at low temperature and thus led to another characteristic of typical spin glass behavior, that is, the decreasing magnetization under a very low magnetic field from Tf to 10 K [8,28,30]. Figure 6 The high coercivity obstructed the magnetization of the samples at low temperature and thus led to another characteristic of typical spin glass behavior, that is, the decreasing magnetization under a very low magnetic field from T f to 10 K [8,28,30].…”

“…The high coercivity obstructed the magnetization of the samples at low temperature and thus led to another characteristic of typical spin glass behavior, that is, the decreasing magnetization under a very low magnetic field from Tf to 10 K [8,28,30]. Figure 6 The high coercivity obstructed the magnetization of the samples at low temperature and thus led to another characteristic of typical spin glass behavior, that is, the decreasing magnetization under a very low magnetic field from T f to 10 K [8,28,30]. Figure 6 The randomly oriented 3d-4f interaction between Nd-Co atoms played an important role as the random anisotropy, and the coupling of these random anisotropy gave rise to the high coercivity as well as the spin-glass-like behaviors in the Nd-Co binary MGs at low temperature.…”

“…That is, the ZFC curve overlapped with the FC curve from room temperature to a certain temperature below the Curie temperature (T c ) and then the two kinds of M-T curves diverged below this temperature. The λ-shaped FC and ZFC M-T curves that appear commonly in Tb (Dy)-based MGs indicate the spin-glass-like behavior in the Nd-Co binary MGs [8,[28][29][30]. The T c and the spin freezing temperature (T f ) of the Nd-Co binary MG ribbons obtained from their M-T curves with a lower ±0.05 K measurement error are summarized in Table 2.…”

“…The magnetocaloric amorphous alloys, as one of the important branches of functional MGs, are ideal candidates for the key working components in a magnetic refrigerator because their broad magnetic entropy change (−∆S m ) peaks and the resulting high refrigeration capacity (RC) are suitable for constructing the flattened −∆S m curves that are essential for the Ericsson cycle used in magnetic refrigeration [6,7]. Moreover, one of the most important advantages superior to the intermetallic compounds is that the MGs can be vitrified within a wide compositional range, and thus their physical properties, especially magnetocaloric properties, are tailorable [8][9][10][11][12]. The magnetocaloric MGs can generally be classified into two categories: the rare-earth (RE)-based and transition metal (TM)-based MGs.…”