Magnetic phase transition in Mn5Ge3(001) film on Si(111)

https://doi.org/10.1016/j.jmmm.2025.173467

This work explores the magnetic phase transition and magnetocaloric properties of epitaxial Mn₅Ge₃ (001) films on Si(111) synthesized via molecular beam epitaxy. Critical exponents (β = 0.34 ± 0.01, γ = 1.05 ± 0.01, δ = 3.82 ± 0.16) exhibit behavior between 3D Ising and Heisenberg models, attributed to anisotropic exchange interactions. Magnetocaloric entropy change (ΔS) and relative cooling power (RCP) were calculated from isothermal magnetization data, yielding ΔS_max = 3.2 ± 0.21 J·kg⁻¹·K⁻¹ and RCP = 91 ± 6 J·kg⁻¹ at 15 kOe, comparable to bulk Mn₅Ge₃. At low field (H < 6 kOe) positive ΔS is observed due to magnetocrystalline anisotropy. At high filed (H = 15 kOe) estimated adiabatic temperature changes (ΔT_ad) is 1.5 ± 0.1 K. The films’ critical indices and magnetocaloric performance align closely with bulk material, demonstrating minimal decrease from interfacial and strain effects. These results highlight Mn₅Ge₃ thin films as possible candidates for rare-earth-free solid-state cooling micro and nanodevices, combining relatively high efficiency and scalable integration into microsystems. The study advances the understanding of thin film magnetocaloric materials for future application in energy-efficient technologies