Abstract-Terahertz radiation by subpicosecond magnetization modulation in a ferrimagnet LiFe5O8

Yuto Kinoshita, Noriaki Kida, Masato Sotome, Tatsuya Miyamoto, Yusuke Iguchi, Yoshinori Onose and Hiroshi Okamoto

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.6b00272?journalCode=apchd5
We report the terahertz radiation in a polar and ferrimagnetic insulating oxide LiFe₅O₈upon irradiation of a femtosecond laser pulse at room temperature. By the resonant optical excitation of an originally spin-forbidden d-d transition in Fe³⁺ ions, we 
observed the emission of terahertz waves, which is attributable to the magnetic-dipole radiation originating from the light-induced subpicosecond magnetization modulation. By mapping out the emission of the terahertz waves, we successfully visualized the vector images of in-plane magnetic domains in magnetic fields. The terahertz-radiation imaging presented here is useful as a new tool to observe ferro- or ferri-magnetic domains.