[19p-H135-1~7] Science and Application of Extreme Nonlinear Phenomena Induced by Intense Terahertz and Infrared Electromagnetic Field

△ [19p-H135-7] Controlling spin dynamics and magnetic order with intense terahertz magnetic fields

〇Takayuki Kurihara¹, Tohru Suemoto¹, Makoto Nakajima² (1.ISSP, Univ. Tokyo, 2.ILE, Osaka Univ.)

Keywords:terahertz,spintronics,metamaterial

Magnetic field contained in the intense THz transient enables the spin precession dynamics to be controlled on a picosecond time scale without causing excess heating of the electronic system. For this feature, it has a potential applicability to the future spintronics devices operating at frequencies far exceeding the conventional level of GHz. However, the perturbation of spin system induced by THz magnetic field in the previous studies have been limited to a tiny fluctuation, and no reports have been made that succeeded in causing the change of magnetization states in a macroscopic level.
Here we demonstrate that by applying an intense THz magnetic field enhanced around split-ring resonator (SRR) on the initial process of the fs laser-induced ultrafast spin reorientation phase transition in ErFeO₃, it is possible to coherently select the path of phase transition process and as a result, macroscopic magnetization can be obtained as the final state of phase transition. Our results present the first demonstration that the intense THz magnetic field has been successfully utilized to control macroscopic magnetization, which paves the way towards the realization of ultrafast spintronics devices such as THz magnetic memory in the future.