We report the broadband emission of terahertz (THz) pulse in metallic patterned ferromagnetic heterostructures CoFeB/Pt based on inverse spin-Hall effect, by illuminating a train of linearly polarized 120-fs-wide laser pulses at 800 nm. The spatial-temporal distribution of charge currents by changing the length of the subwavelength rectangular metal blocks allows for not only effectively controlling the magnitude, but subtly tuning the center frequency and bandwidth of the emitted THz pulses. Our results will open new avenues for the study of modulated spintronic-based THz emitters.
The relativistic inverse spin Hall effect (ISHE) plays a pivotal role in terahertz (THz) emission in magnet/heavy metal bilayers. Here, THz emission from RuO2/Py bilayers is reported due to not only the relativistic ISHE but also the nonrelativistic inverse altermagnetic spin splitting effect (IASSE) in RuO2. For the (100)‐oriented RuO2/Py bilayers, the THz emission is greatly enhanced owing to IASSE once the polarization direction of the spin current (from the Py layer induced by pump laser) is parallel to the Néel vector of RuO2, producing the anisotropic THz emission with twofold symmetry. In contrast, the RuO2(110)/Py bilayer only exhibits isotropic THz emission because of the absence of IASSE‐induced spin‐charge conversion in the (110)‐oriented RuO2 films. Apart from the fundamental significance of exploring the IASSE‐induced spin‐to‐charge conversion, the finding also enriches the physical mechanism and modulation method of THz emission in spintronic systems.
We use terahertz (THz) magnetic and electric fields to investigate the magnetic and optoelectronic responses of the Sm0.5Pr0.5FeO3 (SPFO) crystal, respectively, by THz time-domain spectroscopy. It is found that the spin reorientation transition (SRT) in SPFO occurs in the temperature range of 175–210 K. The SRT is not observed in PrFeO3. The quasi-antiferromagnetic magnon frequency has a blue-shift from 0.42 THz (PrFeO3) to 0.46 THz (SPFO) at room temperature, due to the enhanced anisotropy constant. The refractive index of SPFO in the THz frequency decreases around 3% compared with that of the PrFeO3 crystal. In addition, it can be found that the energy scale of crystal-field transitions has a red-shift for the doped single crystal. We expect our results to make rare-earth orthoferrites accessible to potential applications in THz spintronic devices.
The spin dynamic process of the IrMn/CoFe system has
been investigated
by the time-resolved magneto-optical Kerr effect. It is found that
both spin pumping and the interfacial exchange spring effect between
IrMn and CoFe layers contribute to the total effective Gilbert damping.
With the increase in IrMn layer thickness (t
IrMn), the saturated damping factor initially increases and
subsequently starts to decline beyond 2.4 nm. The results demonstrate
that the damping factor drops due to the exchange spring effect in
the IrMn/CoFe system, where the IrMn layer features additionally as
a spin source when the antiferromagnetic order of the IrMn layer is
built at t
IrMn > 2.4 nm. With an inserted
Cu layer in between, the damping factor behaves differently by remaining
nearly constant in a small range with increasing t
IrMn after its initial increase. This results from the
exchange-decoupling of IrMn and CoFe layers in the presence of a 3
nm thick Cu interlayer and the disappearance of the exchange spring
effect.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.