09:30 〜 11:30
▲ [21a-P02-34] Optical spin generation using Bi/Ag interface
キーワード：Spintronics, Photo-spintronics, Optically-induced spin current
Recently, optical-helicity driven magnetization dynamics in thin film ferromagnets has been reported, which has potential to be used for future photonic-spintronic memory devices. Inverse Faraday effect in ferromagnets and optical spin injection into heavy metals have been observed, which can induce field-like torque and spin-transfer torque on thin film magnetization. In addition to the inverse Faraday effect and optical spin injection, interfacial optical spin generation using the optical Rashba-Edelstein effect was observed recently, which can be induced by spatial inversion symmetry breaking of thin film heterostructure. It was demonstrated that Bi/Ag heterostructure has Rashba interface between two nonmagnetic layers in which optical spin generation due to Rashba spin-orbit coupling at nonmagnetic interface is expected. Here, we study optical spin generation using Bi/Ag interface by measuring optical-helicity driven torques in ferromagnet/Ag/Bi thin film heterostructures.
Thin film samples are made by magnetron sputtering technique. (111) textured Ta(3)/Co(2)/Ag/Bi/Al(3) layers were deposited on thermally oxidized Si substrate (thickness is in nm). Optical-helicity driven torques were measured by all-optical time-resolved magneto-optical Kerr effect. Wavelength and pulse duration of laser pulse used were 800 nm and 120 fs, respectively. Circularly polarized laser pulse is irradiated on thin film samples and magnetization dynamics driven by optical-helicity is detected by stroboscopic pump-probe technique. The phase of magnetization precession induced by circularly polarized laser pulse is reversed when optical-helicity is changed, indicating optical-helicity driven torques. Details of optical-helicity driven torques and comparison with different heterostructures will be discussed in the presentation.
Thin film samples are made by magnetron sputtering technique. (111) textured Ta(3)/Co(2)/Ag/Bi/Al(3) layers were deposited on thermally oxidized Si substrate (thickness is in nm). Optical-helicity driven torques were measured by all-optical time-resolved magneto-optical Kerr effect. Wavelength and pulse duration of laser pulse used were 800 nm and 120 fs, respectively. Circularly polarized laser pulse is irradiated on thin film samples and magnetization dynamics driven by optical-helicity is detected by stroboscopic pump-probe technique. The phase of magnetization precession induced by circularly polarized laser pulse is reversed when optical-helicity is changed, indicating optical-helicity driven torques. Details of optical-helicity driven torques and comparison with different heterostructures will be discussed in the presentation.