We demonstrate the utility of electron irradiation as a tool to enhance device functionality of graphene-analogous MoS2. With the help of first-principles based calculations, vacancy-induced changes of various electronic properties are shown to be a combined result of crystal-field modification and spin-orbital coupling. A comparative theoretical study of various possible vacancy configurations both in bulk and monolayer MoS2 and related changes in their respective band-structures help us to explain plausible irradiation induced effects. Experimentally, various structural forms of MoS2 in bulk, few layered flakes, and nanocrystals are observed to exhibit important modification of their magnetic, transport, and vibrational properties, following low doses of electron irradiation. While irradiated single crystals and nanocrystals show an enhanced magnetization, transport properties of few-layered devices show a significant increase in their conductivity, which can be very useful for fabrication of electronic devices. Our theoretical calculations reveal that this increase in n-type conductivity and magnetization can be correlated with the presence of sulfur and molybdenum vacancies.
A transparent polarisation sensitive phase pattern makes a polarisation dependent transformation of quantum state of photons without absorbing them. Such an invisible pattern can be imaged with quantum entangled photons by making joint quantum measurements on photons. This paper shows a long path experiment to quantum image a transparent polarisation sensitive phase pattern with hyper-entangled photon pairs involving momentum and polarisation degrees of freedom. In the imaging configuration, a single photon interacts with the pattern while the other photon, which has never interacted with the pattern, is measured jointly in a chosen polarisation basis and in a quantum superposition basis of its position which is equivalent to measure its momentum. Individual photons of each hyper-entangled pair cannot provide a complete image information. The image is constructed by measuring the polarisation state and position of the interacting photon corresponding to a measurement outcome of the non-interacting photon. This paper presents a detailed concept, theory and free space long path experiments on quantum imaging of polarisation sensitive phase patterns.
This article reports a compact ultrathin metamaterial absorber with three resonances in S‐band, X‐band, and Ku‐band. The geometry of the proposed absorber consists of a square ring, a splitted square ring, and a plus shaped resonating structure. The plus shaped structure is enclosed within a split ring resonator and it is further enclosed by an outer square ring. The proposed absorber is fabricated on a low cost FR4 substrate of thickness 1 mm that is, 0.011 λlowest (where, λ is the lowest resonating frequency). The size of unit cell is 10 × 10 mm2. It exhibits 99.6%, 99.1%, and 99.1% absorption at 3.4, 9.6, and 13 GHz, respectively. Moreover, the physical insight of the design is explained by surface current distribution and equivalent circuit analysis. Stability of the proposed design is validated with different incident (for transverse electric (TE) and transverse magnetic (TM) modes) angles and different polarization angles. Finally, a prototype of the absorber is fabricated and validated experimentally.
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