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Ensembles of parallel nanowires, consists of the parts from different ferro-magnetic metals (for example-FeNi/Co/FeNi) were obtained by method of template synthesis. It was shown that such samples could be the sources of electromagnetic emission – irradiation of Terahertz range. It could be detected when current passed through the contacts at the sample with these wires. The methods of obtaining nanowires was proposed (two-bath galvanic technique), formation of contact layers at the surface (parallel narrow strips of metal) were proposed. The features of these radiation were investigated–it‘s threshold character, it‘s non-thermal origin and spatial distribution. The calculation was also presented, which demonstrated possibility of detecting of Terahertz irradiation, using ensemble of such nanowires, included ferro-magnetic metal and anti-ferromagnetic metal.

The operation of a spin-injection emitter of electromagnetic oscillations with a Ni/NiO/Fe magnetic tunnel junction was first investigated. Using a nonconducting NiO spacer in a magnetic junction, the effect of the potential difference at the interface between magnetic layers on the efficiency of spin-injection emitters is determined. A model of the investigated emitter is theoretically described and the efficiencies of the emitters with a magnetic tunnel junction and a magnetic junction without an Ni/Fe spacer are experimentally compared. The possibility of enhancing the efficiency of the spin-injection emitter by using the magnetic tunnel junction is demonstrated.

Operating modes of terahertz (THz) generators with “rod–film” magnetic junctions formed by a Fe rod with one pointed end with a diameter of 10–50 nm and various nanometer-thick (single-layer and multilayer) Со films are studied. It is demonstrated that the efficiency of the THz radiation increases (due to an increase in the current density) if the thickness of a single-layer film decreases to the point when it becomes discontinuous (ultrathin) while retains its conductivity. If a multilayer structure with several such films separated by nonmagnetic conductive layers is used, the radiation power can also be increased.

A system of spin-injection emitters employing magnetic junctions based on an array of parallel nanodimensional wires has been studied. Manufacturing technology and possible variants of the nanowire structure are discussed. Conditions of the formation of a new type of spin-injection emitters of terahertz radiation on this basis are considered. The design of the experimental setup is described, and the results of experiments are analyzed. It is established that signals in a 16–18 THz range can be generated by passing high-density current through the proposed nanowire array.

The observation of the stimulated terahertz radiation in magnetic junctions at the room temperature resulting from the current injection of nonequilibrium spins is reported. Contacts between two ferromagnetic layers and between a ferromagnetic and an antiferromagnetic layer are investigated. As the current is increased, first, a narrow isolated radiation peak at terahertz frequencies is observed, which is analogous to the laser peak; then, the peak broadens and its intensity increases by more than an order of magnitude.

The possibility of generation of terahertz electromagnetic waves by the current in a planar structure composed of metalferromagnetic nanoparticles imbedded into an antiferromagnetic medium, is considered.

The magnetostatic field distribution in a structure formed from a ferromagnetic (FM) rod and thin FM film is numerically calculated. The effective terahertz radiation was previously discovered in such a structure in the presence of a current. It is shown that nanodimensional sections of the boundary between the lateral surface of the rod and the surface of the film can be a source of radiation. On these sections, the magnetostatic field changes its direction, a circumstance that provides for conditions for radiative transitions of electrons.

Spin injection mechanisms for radiation and detection of terahertz waves based on magnetic nano junction are considered. High efficiency of terahertz radiation is theoretically explained and the method of the detection of this radiation is offered. The device of the spin injected terahertz radiators is presented.

A method for the measurement and identification of the radiation frequencies of the spin-injection oscillator in the terahertz frequency range using a diffraction grating is developed and experimentally implemented. For the system consisting of a ferromagnetic rod (Fe) and nanosized ferromagnetic film (Fe3O4 with a thickness of up to 100 nm), the thermal and dynamic components of the radiation that is induced by the current flow are separated. The diffraction peaks at a frequency of about 9.6 THz and a band of 37% at a level of 3 dB and at a frequency of 43.5 THz are demonstrated. It is shown that the intensity of each signal is significantly higher than the thermal background level.

The energy efficiency of the spin-injection emitter based on the rod-film ferromagnetic structure with a point contact between the components in the terahertz frequency range is experimentally estimated. The film material substantially affects the efficiency. A concentrator of magnetic flux is proposed for an increase in the efficiency. The experimental estimations allow the quantum yield of the emitter that is greater than unity. This result indicates significant contribution of the stimulated radiative transitions.

The generation of electromagnetic THz waves by a current is experimentally investigated in planar structures comprised of two ferromagnetic films. When the films come into contact with a thin copper rod, the current is applied to both layers. The first layer, which plays the role of an injector, polarizes the spins of the current carriers. In the second working layer, the conditions are created for spin population inversion and the generation of THz waves. At a current of 350 mA, the radiation wavelength is 16.4 THz and a power of 10 mW is reached at room temperature.

The possibility of terahertz generation in orotron operating on high-order space harmonics is considered. Experimental results for orotron operation on the second space harmonic in short-wave part of millimeter wavelength band are presented.

The experimental study of orotron tuning in 90 - 145 GHz frequency range is carried out for accelerating voltages up to 20 kV. Two period values of two-row periodic structures and three values of inter-row spacing have been investigated as well.

The well-known mechanism of frequency tuning in orotron needs to be corrected where the power devices are concerned. The first peculiarity is connected to the use of a two-row open periodic structure (OPS) that may be considered as a coupled-cavity chain having narrow (resonance) passbands. The condition of a double resonance when the proper frequency of open resonator (OR) coincides with the resonance of OPS may produce break elevation of output power and efficiency of orotron. The second effect is connected to the construction of OR in power orotrons where the length of OPS is chosen to be of the order of spherical mirror aperture. In such a case when the beam voltage augments (for given OPS period) the radiation angle is changed too increasing so-called "dynamic" diffraction losses that limit the range of orotron frequency tuning.

Presented in this paper are the results of experimental study of power two-stage resonance amplifier with a new type of periodic structure operating in 8-mm wavelength range. Authors give advices on the increase of amplifier operation efficiency on the basis of starting currents analysis for each stage.

The first results on experimental investigation of two-stage resonance generator and amplifier have been demonstrated recently. The electrodynamics system was composed of two identical stages formed by open resonator (OR) and lamella-type periodic structure (PS) situated on a plane mirror. The milling technology of PS had provided a period accuracy of the order of 5-6%. As we determined by modeling such period accuracy may be the origin of bad device efficiency and gain by reason of bad synchronism mechanism. In addition the inaccuracy of beam transfer channel height limited the beam current. To improve the PS period and channel accuracy up to 0.7% we modified the design and used the electrospark technology. The search of optimal gain and efficiency regimes by computer-aided design is covered.

than speed of light C. But their use demands a quantitive evaluationof radiation intensity.The many-wave regimes are rather widely used in the relativisticstrong-current electronics providing a high—efficient electron—waveinteraction. But until now the radiation intensity calculation doesn'ttake into acount resonances in these regimes. Therefore (as first —