Wear is an important phenomenon that affects the efficiency and life of all moving machines. In this regard, extensive efforts have been devoted to achieve the lowest possible wear in sliding systems. With the advent of novel materials in recent years, technology is moving toward realization of zero wear. Here, we report on the development of new functional coatings comprising periodically stacked nanolayers of amorphous carbon and cobalt that are extremely wear resistant at the micro and macro scale. Because of their unique structure, these coatings simultaneously provide high elasticity and ultrahigh shear strength. As a result, almost zero wear was observed even after one million sliding cycles without any lubrication. The wear rate was reduced by 8-10-fold compared with the best previously reported data on extremely low wear materials.

We fabricated and characterised nanowire superconducting single-photon detectors (SSPDs) made of 4 nm thick amorphous Mo x Si 1−x films. At 1.7 K the best devices exhibit a detection efficiency up to 18% at 1.2 µm wavelength of unpolarised light, a characteristic response time of about 6 ns and timing jitter of 120 ps. The detection efficiency was studied in wavelength range from 650 nm to 2500 nm. At wavelengths below 1200 nm these detectors reach their maximum detection efficiency limited by photon absorption in the thin MoSi film.

We developed the model of internal phonon bottleneck to describe the energy exchange between the acoustically soft ultra-thin metal film and acoustically rigid substrate. Discriminating phonons in the film into two groups, escaping and non-escaping, we show that electrons and non-escaping phonons may form a unified subsystem, which is cooled down only due to interactions with escaping phonons, either due to direct phonon conversion or indirect sequential interaction with an electronic system. Using an amplitude-modulated absorption of the sub-THz radiation technique, we studied electron-phonon relaxation in ultra-thin disordered films of tungsten silicide. We found an experimental proof of the internal phonon bottleneck. The experiment and simulation based on the proposed model agree well, resulting in e−ph~ 140-190 ps at C = 3.4 K supporting the results of earlier measurements by independent techniques. downslide, until the excited volume containing highly non-equilibrium quasiparticles and phonons, termed as a hotspot, is formed [15]. The details of this process play an important role in SNSPDs and were the focus of recent work [18], where the dominant role of electron-phonon interactions over electron-electron interactions was emphasized even in strongly disordered NbN and WSi where electron-electron interaction is strongly enhanced. Another aspect of hotspot formation is phonon loss into a substrate, defining energy density and hence equilibration rates [18] and fluctuations [19]. The energy exchange between the film and the substrate controls the nucleation and growth of normal domain, resulting in photon count. The latter is also influenced by the strength of electron-phonon, phonon-electron interactions and phonon escape from the film. For this reason, studying electron-phonon interaction and cooling of non-equilibrium electron and phonon distributions in materials, which are used for radiation detection is one of the central problems for all sensors.A new class of amorphous superconductors for SNSPDs, and in the first instance WSi, attracted immediate attention. Subsequently, electron-phonon interaction in WSi was studied by applying pump probe [20] and magnetoconductance [21] measurements, while the detection mechanism was investigated with quantum detector tomography [22]. The experimental work [20] utilised a time resolved two-photon detection technique to study the evolution of the hotspot in current-carrying nanowire under the conditions that the nanowire remains superconducting. Relaxation times of the order of hundreds of picoseconds were found and interpreted in [23] using the kinetic model of hotspot relaxation, where self-recombination of non-equilibrium quasiparticles plays a dominant role. The characteristic electron-phonon time 0 [24], which depends on material, was found to be 0.84 -1.0 ns [20] for tungsten rich WSi. . Thus, electron-phonon relaxation in WSi turned out to be slow in comparison with conventional SNSPD materials, such as NbN and NbTiN (where the measured time of relaxation of ...

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The phenomenon of surface self-healing in C60-based polymer coatings deposited by ion-beam assisted physical vapor deposition was investigated. Nanoindentation of the coatings led to the formation of a protrusion rather than an indent. This protrusion was accompanied by an abnormal shape of the force-distance curve, where the unloading curve lies above the loading curve due to an additional force applied in pulling the indenter out of the media. The coatings exhibited a nanocomposite structure that was strongly affected by the ratio of C60 ion and C60 molecular beam intensities during deposition. The coatings also demonstrated the dynamic hardness effect, where the effective value of the hardness depends significantly on the indentation speed.