We report the first experimental observation of superconductivity in Cd3As2 thin films without application of external pressure. Surface studies suggest that the observed transport characteristics are related to the polycrystalline continuous part of investigated films with homogeneous distribution of elements and the Cd-to-As ratio close to stoichiometric Cd3As2. The latter is also supported by Raman spectra of the studied films, which are similar to those of Cd3As2 single crystals. The formation of superconducting phase in films under study is confirmed by the characteristic behavior of temperature and magnetic field dependence of samples resistances, as well as by the presence of pronounced zero-resistance plateaux in dV /dI characteristics. The corresponding Hc−Tc plots reveal a clearly pronounced linear behavior within the intermediate temperature range, similar to that observed for bulk Cd3As2 and Bi2Se3 films under pressure, suggesting the possibility of nontrivial pairing in the films under investigation. We discuss a possible role of sample inhomogeneities and crystal strains in the observed phenomena.Weyl and Dirac semimetals (WSM and DSM) currently attract wide interest related to the existence of Dirac nodes in their electron spectrum and related nontrivial topological characteristics of both bulk and surface states [1][2][3]. A special attention is drawn to the Cd 3 As 2 compound, which proved to be air-stable, unlike some other DSM materials [4][5][6][7][8]. This compound is known and has been studied for quite a long time [9][10][11][12]. Nevertheless, it is still very popular since the Dirac nodes of this semimetal are protected by the crystal symmetry and the electron states exhibit interesting topological properties, such as spin-momentum locking. Due to the high symmetry, DSM materials can undergo transitions to other topological phases (e.g. WSM) as a result of breaking certain symmetries or applying some external factors.The existence of topologically protected electron states gives a new impetus to the problem of topological superconductivity (TSC) being discussed for a long time [13][14][15]. In particular, Refs. [16,17] provide a theoretical analysis of the possible types of SC pairing in the systems of Cd 3 As 2 type, including topologically nontrivial ones. Basically, the existence of nontrivial pairing potential (leading to the emergence of triplet Cooper pairs) should induce the formation of Majoranna modes at the surface of the crystal, which can be used in the faulttolerant quantum computing [14]. The SC phase emergence in Cd 3 As 2 was reported in Ref.[18], however, it was observed at pressures above the structural transition from the tetragonal to trigonal phase. While theoretical works suggest the stabilization of TSC phase upon such symmetry lowering [16,17], such transition also implies appearance of the gap at Dirac nodes, thus, suppressing the DSM phase. Additional indications of the SC phase in Cd 3 As 2 were also observed in the point-contact spectroscopy experiments and att...

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Electrically conductive amorphous carbon nitride (a-CN) coatings were deposited onto various substrates by pulsed vacuum-arc sputtering of a graphite cathode with simultaneous irradiation of the substrate with nitrogen ions. Deposition temperature was less than 60 • C. We investigated the effect of vacuum annealing at a temperature of 600 • С on the elemental composition, structure, electrical and optical properties of the obtained films. It was found that the elemental composition of the coating practically does not change over the thickness of the coating after annealing, while the remaining characteristics change significantly. Of particular interest is the correlation between the change in the nanostructure of the coating and the electrical properties of the coating. An explanation of the mechanisms for changing the properties of the coating after annealing is proposed.

the dielectric permittivity far from the MIT κ 0 =10.7, the mean acceptor energy » E 42 0 meV and the mean density of the localized states » -( ) g 1.7 6.5 10 16 meV −1 cm −3 .

Charge carriers parameters on a 2D-layer surface for (Cd 1−x−y Zn x Mn y ) 3 As 2 (y=0.08) (the concentration n D 2 =1.9×10 12 cm -2 , the effective value of the 2D-layer = d n n

Features in the transverse magnetoresistance of single-crystalline diluted magnetic semiconductors of a (Cd1–x–yZnxMny)3As2 system with x + y = 0.3 have been found and analyzed in detail. Two groups of samples have been examined. The samples of the first group were thermally annealed for a long time, whereas the samples of the second group were not thermally annealed. The Shubnikov–de Haas (SdH) oscillations were observed for both groups of the samples within a 4.2 ÷ 30 K temperature range and under transverse magnetic field sweeping from 0 up to 11 T. The value of a phase shift, according to the SdH oscillations, was found to be a characteristic of the Berry phase existing in all the samples, except the unannealed sample with y = 0.08. Thickness of 2D surface topological nanolayers for all the samples was estimated. The thickness substantially depended on Mn concentration. The experimental dependence of reduced cyclotron mass on the Fermi wave vector, extracted from the SdH oscillations for the samples with different doping levels, is in satisfactory agreement with the predicted theoretical linear dependence. The existence of the Dirac fermions in all the samples studied (except the unannealed sample with y = 0.08) can be concluded from this result.

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