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Optically detectable magnetic resonance spectra were measured for ensembles of NV-centers in CVD diamonds with different 13C contents. The obtained spectra were described using a model based on the spin Hamiltonian. The magnitude of the magnetic field applied to the sample was estimated using the constructed model and experimental data. [ABSTRACT FROM AUTHOR]

Individual electron–nuclear spin systems in solids are promising platforms for implementation of second-generation quantum technologies. The recognized leader among such systems is the negatively charged nitrogen–vacancy color center (NV center) in diamond with hyperfine coupling to nuclear spins of carbon-13 (13C), which are widely used as a quantum memory in emerging quantum technologies because of their weak interaction with the environment. Recently, pairs of 13C–13C nuclei (dimers) in diamond with NV centers have been proposed and actively studied for this purpose because they have extremely long coherence times (minutes at room temperature) in the singlet state. The eigenstates of the spin Hamiltonian of the NV–13C–13C system were found and used to calculate the probabilities of EPR transitions between nuclear-spin sublevels of NV-center states with electron spin projections mS = 0 and mS = –1. The obtained expressions form the basis for choosing the optimal parameters of microwave and radiofrequency pulses transforming a particular dimer into the singlet state. An example of such a prediction for a specific NV–13C–13C spin system using data for the spatial positions of the 13C spins and the internal spin–spin couplings obtained earlier by quantum chemistry methods is presented. [ABSTRACT FROM AUTHOR]

A method of vector magnetometry implemented using a single NV–13C spin system in diamond is proposed. The method is based on a priori knowledge of the hyperfine interaction characteristics and on the presence of experimentally measured line positions in the optically detectable magnetic resonance spectrum of such a system. The method was experimentally tested on an NV–13C system in which a 13C atom was located in the third coordination sphere of the NV-center. [ABSTRACT FROM AUTHOR]

A method for estimating the isotopic composition and concentration of NV-centers in diamond using Raman scattering and photoluminescence spectra is presented. The spatial distribution of the 13C isotope and NV-centers in CVD-diamond samples with isotopically modified layers was studied using the proposed laboratory technique. [ABSTRACT FROM AUTHOR]

With the use of sol–gel method BaTiO3–SiO2 multilayer structures were fabricated on glass or fused silica substrates employing dipping or spinning procedure. The photonic stop band was observed in the reflection and transmission spectra of the multilayer structure annealed at 4 5 0 ∘ C. It is redshifted with an increase of the thicknesses of BaTiO3 and SiO2 layers. For structures comprising Eu-doped BaTiO3 layers of different thicknesses photoluminescence with the main band at 614 nm was detected. It is characterized with the double-exponential decay with the lifetimes of about 0.5 ms and 1.1 ms which do not depend significantly on the photonic stop band position. [ABSTRACT FROM AUTHOR]

Deep trap spectra in AlGaN/GaN high electron mobility transistor structures grown on Si by metalorganic chemical vapor deposition show four major electron traps (Ec--0.15, 0.29, 0.40 and 0.76 eV) in the AlGaN barrier/interface region and three (Ec--0.18, 0.27 and 0.45 eV) in the undoped GaN buffer region. The presence of a high density of deep acceptor traps was observed in the AlGaN barrier region, as determined by hysteresis in low temperature capacitance-voltage (C-V) characteristics. The spectral dependence of persistent photocapacitance shifts showed two optical thresholds of 1.5V and 3.1 eV, with the second being specific to structures grown on Si substrates. Comparison of results obtained on transistors and on large-area Schottky diodes prepared on heterostructures from which transistors are fabricated show that measurements on test large-area diodes are representative of the main characteristics important for transistor performance. [ABSTRACT FROM AUTHOR]