Optical absorption, Raman spectroscopy, and surface morphology of Dy3Fe5O12 single crystals

The optical properties of Dy 3 Fe 5 O 12 single crystals have been investigated using a combined approach comprising optical absorption spectroscopy, Raman spectroscopy, and atomic force microscopy. The absorption spectra measured in the 200–1100 nm range reveal a pronounced separation between high-energy and low-energy electronic excitations. The ultraviolet–visible region is dominated by intense electronic transitions within the Fe–O sublattice, which may include both ligand-to-metal charge-transfer and correlation-driven intersite contributions. In contrast, the near-infrared region exhibits weak absorption features attributed to intra-ionic 4f–4f transitions of Dy 3+ ions. Raman spectroscopy confirms the high structural quality of the crystals through the presence of well-resolved phonon modes with low linewidths, while atomic force microscopy demonstrates a morphologically homogeneous surface with no periodic modulation that could induce optical artifacts. These results collectively support the interpretation that the observed spectral features originate predominantly from intrinsic bulk electronic and lattice properties. The combined analysis reveals a clear decoupling between Fe–O-derived electronic excitations and localized Dy 3+ states, which dominate different spectral regions. This separation provides a consistent framework for interpreting the optical response of rare-earth iron garnets. The results also highlight the limitations of room-temperature measurements for resolving the microscopic origin of high-energy transitions, indicating the need for further temperature- and polarization-dependent studies.