Specific heat of Gd₄Co₃

Abstract

The specific heat (C(T)) of Gd₄Co₃ was measured in the temperature range 2-300 K and its magnetic contribution (C(m)(T)) was determined using a new method that fits the electronic specific heat coefficient (γ) and the Debye temperature (θ(D)) by constraining the resulting magnetic entropy (S(m)(T)) to saturate at temperatures far above the Curie temperature (T(C)). C(m)(T) exhibits a low-temperature bump originating from thermal excitation of gapped spin waves, which is responsible for pronounced peaks, at ≈35 K, in both C(m)/T and the temperature derivative of the magnetic contribution to electrical resistivity (dρ(m)/dT). Apart from in the vicinity of T(C), an excellent global correlation was found between C(m)/T and dρ(m)/dT. Our results provide strong support for the consistency of the new method proposed for the determination of C(m)(T) and rule out any major role of short-range order on Gd moments or d-electron spin fluctuation effects in the paramagnetic phase. A comparative analysis with other methods used in similar compounds points to the need for a better evaluation of C(m)(T) in such compounds, especially in the magnetically ordered phase, where a deficient evaluation of C(m)/T has a larger impact on the S(m)(T) curve.

Stabilization by Si Substitution of the Pseudobinary Compound Gd2(Co3–xSix) with Magnetocaloric Properties around Room Temperature

“…31 The inset of Figure 10 presents the low-temperature (T ≪ θ D ) linear fits of C/T(T 2 ), which correspond to the fitting parameters γ A = 20(4) mJ K −2 mol(at) −1 , γ B = 9.1(2) mJ K −2 mol(at) −1 , θ DA = 239(4) K, and θ DB = 228(4) K. As can be seen in the expanded view shown in the inset of Figure 10, the C/T versus T 2 representation for the sample Gd 1.99 Co 2.58 Si 0.44 presents an upward deviation below 4 K that has not been considered in the fitting procedure. This deviation of the low-temperature linear behavior has been also found in the literature in Gd-based intermetallic compounds 32 and needs further study. The specific heat for Gd 2.00 Co 2.52 Si 0.49 (sample A) was not measured to such a low temperature, and hence this upward deviation was not observed.…”

Thermoelectric power of Gd4(Co1-xCux)3 compounds

“…11 This clearly indicates that the low temperature electron transport behavior of these compounds is dominated by strong magnon-induced s-d electron scattering. 11 This clearly indicates that the low temperature electron transport behavior of these compounds is dominated by strong magnon-induced s-d electron scattering.…”

Sub-picosecond exchange–relaxation in the compensated ferrimagnet Mn2Ru x Ga

“…Initially, we used the set of G-parameters of GdCoFe for the coupling constants [1,28]. For the specific heat capacities of lattice and electron systems, C l and C e , we used values for Mn 2 Ga single crystals [29], shown in table 1, where the heat capacity of the electron system is indicated trough γ e = C e /T e -the proportionality factor.…”