Speaker
Description
Abstract
The polycrystalline Ce₂Al₃Ge₄ compound has been synthesized by arc-melting. The structural, magnetic and critical behavior properties have been investigated through measurements of X-ray diffraction (XRD), magnetic susceptibility, χ(T), magnetization, M(μ₀H), and heat capacity, Cₚ(T). The structure has been obtained and refined from XRD pattern in the Cmcm – D₂h No. 64 space group with a = 6.08118(6) Å, b = 15.086(2) Å and c = 7.986(1) Å. The DC and AC-χ(T) as well as the Cₚ(T) data indicate a ferromagnetic (FM) transition at around T_c = 9.9 K. Below T_c, an additional magnetic phase transition temperature around T₁ = 5.4 K was observed and attributed to FM rearrangement of the Ce moment. χ(T) data at high temperature follows the modified Curie – Weiss relationship, giving an effective magnetic moment smaller than that expected for the trivalent Ce ion. Cₚ(T) data at low temperatures below T₁ can be well described according to the spin-wave magnon model with energy gap Δ_c = 4.6(1) K, and at high temperatures, well above T_c, by the Debye-Einstein Model, giving a Debye and Einstein temperatures, θ_D = 197(20) K and θ_E = 300(26) K, respectively. The standard Arrot plots indicates a second-order phase transition. The critical behaviour study around the FM phase transition using the mean-field and the Kouvel – Fisher methods yields the average critical exponents β = 0.614, γ = 1.002, and δ = 2.631 close to those expected for a 3D mean – field ferromagnet. The resulting average value of T_c = 7.11 K obtained from the critical behaviour study is roughly equal to the average value of the two magnetic phase transition temperatures T₁ and T_c obtained from χ(T) and Cₚ(T) data.
Key words:
Ferromagnetism, Heat capacity, Spin-wave, Magnetic susceptibility, Magnetization, Critical behaviour, Mean-field model, Critical exponents.
| Apply for student award at which level: | PhD |
|---|---|
| Consent on use of personal information: Abstract Submission | Yes, I ACCEPT |