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.

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.

Two-dimensional transition metal dichalcogenides (TMDs) and alloys based on them, is a promising platform for creating opto- and nanoelectronic devices. For layered alloys, there is a strong need to theoretically determine the frequencies of vibrational modes and dependences of their energies on the stoichiometric composition. By comparing experimentally measured Raman modes with theoretical predictions, it becomes possible to determine the stoichiometric composition of the manufactured alloys. In this work, we investigated the vibrational properties of monolayer MoS_2x Se_2(1−x) alloys utilizing density functional theory method and confirmed them experimentally by Raman spectroscopy. The dependence of A₁ʹ and E¹ _2g ‘dactylographic’ modes on the stoichiometric composition of alloys has been calculated. When in pure MoSe₂ structure Se atoms are substituted by S atoms, the in-plane E¹ _2g (S–Mo), E¹ _2g (Se–Mo) and out-plane A₁ʹ (S–Mo) modes shifted linearly in x to higher frequencies, while the out-plane A₁ʹ (Se–Mo) mode did the same in nonlinear way. We also identified the E¹ _2g (Se–Mo–S) mode, which specific for the MoS_2x Se_2(1-x) alloys and does not appear in pure two-component TMDs.