Carrier Dynamic studies on rare earth EuAl₄ thin films revealing absorption dynamics

EuAl₄ thin films exhibit strong magnetic ordering originating from Eu²⁺ ions, making them useful for spintronic and quantum material studies. Their unique combination of metallic conductivity and low-symmetry crystal structure gives rise to unusual magneto-transport behaviors. Thin-film growth enables tuning of the magnetic and electronic properties through strain and layer engineering, which is essential for exploring two-dimensional magnetism and interfacial effects. In this work, EuAl₄ thin films of various thicknesses were prepared by pulsed-laser deposition (PLD) and subsequently studied using a pump–probe technique to extract the carrier dynamics of the thin films, in comparison with those of the single crystal. Both reflectance (ΔR/R) and transmission (ΔT/T) measurements, showing that the probing photon (1.2 eV) intensity increases upon excitation by pumping photons (2.4 eV), reveal the absorption dynamics characterized by an intensity dip before recovery to equilibrium. The fast decay time τ₁ in all films is less than 10 ps, consistent with the carrier dynamics observed in EuAl₄ single crystals. However, the slower decay time τ₂ (>150 ps) differs between the single crystals and thin films, and the thermal effects contributing to this behavior will be discussed. This work lays the foundation for probing carrier dynamics in abundant magnetic phases of rare-earth films by placing the samples in temperature-dependent environments and applying external magnetic fields in future studies