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▼ [16p-D419-13] Spintronic THz emitter with L12-ordered antiferromagnetic Mn3Ir
Keywords:terahertz, antiferromagnet, spintronics
A spintronic THz emitter with a ferromagnetic metal/heavy metal heterostructure emits a single-cycle terahertz (THz) electromagnetic wave due to the temporal fluctuation of charge current. [1] Hence, the charge current is converted in the heavy metal layer from an optically generated spin current pulse with a sub-picosecond duration. This ultrafast spin-charge conversion through the inverse spin Hall effect can be enlarged by increasing the spin conversion efficiency in the heavy metal layer. While the spintronic THz emitter conventionally developed with nonmagnetic heavy metals, the capability of the L12-ordered antiferromagnetic Mn3Ir has not been explored despite the large anomalous spin Hall effect and spin-orbit coupling of Ir [2].
Here, we report the emission of THz waves originating in the ultrafast spin-charge conversion inside an L12-ordered antiferromagnetic Mn3Ir layer. A 15-nm thick Mn3Ir(111) layer was grown on a MgO(111) substrate at 600℃ by the dc sputtering method. A 3-nm thick permalloy (Py) and 5-nm thick SiO2 capping layers were then deposited at room temperature. Yb: KGW laser system with a central wavelength of 1028 nm was used for the spin current excitation under applying an in-plane magnetic field of 0.5 kOe by a permanent magnet. Electro-optic sampling technique with a CdTe(110) single crystal was used to measure the form of the emitted THz waves.
Figure 1 displays that the observed THz waveforms depend on the polarity of an external magnetic field, in contrast to no single for a Mn3Ir/Pt multilayer. These results mean that the THz waves originate in the charge conversion of the spin currents from the Py layer. The Mn3Ir layer is not a spin source but the spin-charge conversion layer.
[1] T. Kampfrath et al., Nat. Nanotechnol. 8, 256-260 (2013).
[2] H. Iwaki et al., Appl. Phys. Lett. 116, 022408 (2020).
Here, we report the emission of THz waves originating in the ultrafast spin-charge conversion inside an L12-ordered antiferromagnetic Mn3Ir layer. A 15-nm thick Mn3Ir(111) layer was grown on a MgO(111) substrate at 600℃ by the dc sputtering method. A 3-nm thick permalloy (Py) and 5-nm thick SiO2 capping layers were then deposited at room temperature. Yb: KGW laser system with a central wavelength of 1028 nm was used for the spin current excitation under applying an in-plane magnetic field of 0.5 kOe by a permanent magnet. Electro-optic sampling technique with a CdTe(110) single crystal was used to measure the form of the emitted THz waves.
Figure 1 displays that the observed THz waveforms depend on the polarity of an external magnetic field, in contrast to no single for a Mn3Ir/Pt multilayer. These results mean that the THz waves originate in the charge conversion of the spin currents from the Py layer. The Mn3Ir layer is not a spin source but the spin-charge conversion layer.
[1] T. Kampfrath et al., Nat. Nanotechnol. 8, 256-260 (2013).
[2] H. Iwaki et al., Appl. Phys. Lett. 116, 022408 (2020).