@article{oai:ynu.repo.nii.ac.jp:00004170,
 author = {Minami, Yasuo and Takeda, Jun and Dao, Thang Duy and Nagao, Tadaaki and Kitajima, Masahiro and Katayama, Ikufumi},
 issue = {24},
 journal = {Applied physics letters},
 month = {Dec},
 note = {Linear and nonlinear electron dynamics of polycrystalline gold (Au) ultrathin films with thicknesses ranging from 1.4 to 5.8 nm were investigated via transmittance terahertz (THz) spectroscopy with intense electric field transients. We prepared ultrathin films with low surface roughness formed on a Si-(7×7) reconstructed surface, leading to the observation of monotonic decrease in THz transmittance with respect to film thickness. Furthermore, at all tested thicknesses, the transmittance decreased nonlinearly by 10%-30% with the application if high-intensity THz electric fields. Based on a Drude-model analysis, we found a significant decrease in the damping constant induced by the THz electric field, indicating that electrons are driven beyond the polycrystalline grain boundaries in Au thin films, and consequently leading to the suppression of the electron-boundary scattering rate.},
 title = {Nonlinear electron dynamics of gold ultrathin films induced by intense terahertz waves},
 volume = {105},
 year = {2014}
}