和達 大樹

<jats:p>The crystal structure of La4Ge3S12 has been known to be noncentrosymmetric for almost four decades. This characteristic inversion symmetry breaking suggests the presence of nonlinear optical (NLO) properties. Yet, experimental observations of such phenomena, including second harmonic generation (SHG) have been reported only in recent studies. In this study, we synthesized La4Ge3S12 using the one‐step melting method, which is more straightforward than the conventional two‐step growth method. We characterized the composition, crystal structure, and electronic structure using electron probe microanalysis, powder X‐ray diffraction, and X‐ray photoelectron spectroscopy. The experimental electronic structure is in line with those obtained using first‐principle calculations. In addition, we observed the NLO properties of La4Ge3S12 in response to the ultrashort pulsed infrared laser. We found that the intensity of the SHG quadratically depends on the intensity of the incident light, mirroring the intrinsic nature of NLO.</jats:p>

Rocksalt-type heavy rare earth monoxides REOs (RE = Tb, Dy, Er) were synthesized as single phase epitaxial thin films for the first time. They exhibited metallic electronic states and a much higher T_C than the corresponding rare earth nitrides.

Abstract In the present study, we investigated the magnetization dynamics of a Gd₂₃Fe₆₇Co₁₀ nanofilm. We subjected the nanofilm to a time-resolved experiment to examine its magneto-optical effect using an X-ray free electron laser. By tuning the energy of the photons to the core-level resonance of the Fe absorption edge, we selectively determined the magnetic behavior of the elements at the Fe site in the nanofilm. When triggered by an ultrashort pulse of infrared radiation, the materials underwent demagnetization and magnetic reversal, depending on fluence of the laser. The following relaxation process was found to be associated not only with the fast recursion but also with a long sustention of the reversed magnetization. The experimental observation consistently match with the recent prediction by the magnetic dynamic simulation. The ultrafast dynamics was triggered by the ultrafast thermal effect and it was recovered toward the initial state in the non-thermal manner.