We report on the design of a spintronic emitter based on the Pt(3 nm)/Co(3 nm) structure, which enables the control over terahertz radiation polarization. Utilizing the field-induced magnetization rotation that takes place at low magnetic fields of up to 250 Oe at room temperature, we have achieved the full range of terahertz polarization rotation from 0° to 360°. This rotation became possible due to the uniaxial magnetic anisotropy induced in the plane of the cobalt film during its fabrication. We evaluated the efficiency of the Co/Pt structure in generating terahertz radiation and found that the terahertz pulse energy flux reaches ∼160 nJ/cm2 at an excitation flux of 4 mJ/cm2.

The control and monitoring of the polarization of terahertz radiation are of interest for numerous applications. Here we present a simple controllable THz emitter with a small coercive magnetic field. It is based on a Co/WS₂/silicon structure, in which the presence of uniaxial magnetic anisotropy caused by mechanical stress in a ferromagnetic film was found. Our results show that a ferromagnet/semiconductor emitter can become a technologically simple device for terahertz spintronics.

In this article, we investigate optically induced terahertz radiation in ferromagnetic FeCo layers of varying thickness on Si and SiO₂ substrates. Efforts have been made to account for the influence of the substrate on the parameters of the THz radiation generated by the ferromagnetic FeCo film. The study reveals that the thickness of the ferromagnetic layer and the material of the substrate significantly affect the generation efficiency and spectral characteristics of the THz radiation. Our results also emphasize the importance of accounting for the reflection and transmission coefficients of the THz radiation when analyzing the generation process. The observed radiation features correlate with the magneto-dipole mechanism, triggered by the ultrafast demagnetization of the ferromagnetic material. This research contributes to a better understanding of THz radiation generation mechanisms in ferromagnetic films and may be useful for the further development of THz technology applications in the field of spintronics and other related areas. A key discovery of our study is the identification of a nonmonotonic relationship between the radiation amplitude and pump intensity for thin films on semiconductor substrates. This finding is particularly significant considering that thin films are predominantly used in spintronic emitters due to the characteristic absorption of THz radiation in metals.

We present a novel spin-valve THz emitter composed of FeCo/TbCo2/FeCo tri-layers separated by a copper spacer, designed to provide amplitude modulation of THz radiation. The distinct coercivities of the magnetic layers enable magnetic field control of the THz emission, with the final amplitude formed by the interference of THz waves from the individual tri-layers. Experimental studies using time-domain spectroscopy reveal that the spin-valve structure, optimized for in-plane magnetic anisotropy, effectively modulates the THz signal and maintains constant polarization. Although the current optical-to-THz conversion efficiency is insufficient for commercial use, the findings offer crucial insights for enhancing efficiency through structural optimization, highlighting the potential for advanced THz emitters and modulators.

We demonstrate an efficient THz spintronic emitter using a Co/WSe2 heterostructure that enables direct control of the emitted THz polarization. The device is excited by femtosecond laser pulses and leverages spin-to-charge conversion at the Co/WSe2 interface to generate broadband THz pulses. We observe that the THz emission polarization can be continuously tuned via the magnetization orientation without significant loss in intensity. At higher pump fields, nonlinear optical effects in the WSe2 layer contribute to the THz output, indicating an emission enhancement beyond the conventional spintronic mechanism.

In this work, the optical parameters of a 550 μm thick deuterated triglycine sulfate (DTGS) crystal in the range of 0.3–1.5 THz were investigated in low and high fields by time-domain spectroscopy. The X and Z axes of the refractive index ellipsoid were identified, and the refractive indices and extinction coefficients were determined. In addition, it was shown that, in strong THz fields, a phonon A-mode with a frequency of about 40 cm⁻¹ can be excited in the DTGS crystal when the THz wave vector coincides with the polar axis of the crystal and the polarization of the THz radiation coincides with the X-axis of the crystal. The use of the observed effect and the determination of the mode excitation parameters can be twofold. First, they show the limits of the THz field for non-invasive action on the crystal. Second, they present the mode excitation conditions that can be used, for example, in controllable absorbers.