[22p-E304-1~6] Imaging by using from visible light to X-rays - Exploring its versatility-

△ [22p-E304-3] Time- and space- resolved magnetic domain in laser-irradiated NiCo₂O₄ thin films

〇Ryunosuke Takahashi¹, Hirotaka Abe¹, Yoshiki Tani¹, Minato Yamasaki¹, Takuo Ohkochi^3,4, Daisuke Kan², Yuichi Shimakawa², Hiroki wadati^1,5 (1.Univ. of Hyogo, 2.Kyoto Univ., 3.JASRI, 4.RIKEN, 5.Osaka Univ.)

Keywords:Ultrafast, magnetic domain

The ferrimagnetic oxide NiCo₂O₄ thin film exhibits perpendicular magnetic anisotropy and is known as a half metal. It is expected to be applied to high-density magnetic recording devices, including chemical stability. We irradiated this thin film with an infrared pulsed laser, and performed microscopic observations and time-resolved measurement to observe the dynamics of laser effect on the femtosecond scale. Time-resolved measurements show ultrafast demagnetization of 0.4 ps, which is 100 to 1000 times faster than previous reported half-metallic oxides. It is suggested that it is derived from metallic electronic states different from general oxides and spin polarization. From microscopic measurements, when the temperature was raised to 380 K, ring-shaped all-optical magnetization switching appeared around the demagnetized area, and the important relationship between magnetic domain size, temperature and laser effect can be predicted.