All-optical dc nanotesla magnetometry using silicon vacancy fine structure in isotopically purified silicon carbide

We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-$^{28}$SiC) and find extra terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3/2 color center. These terms give rise to additional spin transitions, which are otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity of 87 nT Hz$^{-1/2}$ within a volume of $3 \times 10^{-7}$ mm$^{3}$ at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radiofrequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3 mm$^{3}$ the projection noise limit is below 100 fT Hz$^{-1/2}$.Comment: 12 pages, 6 figures; additional experimental data and an extended theoretical analysis are added in the second versio

Nonlinear Bogolyubov-Valatin transformations and quaternions

In introducing second quantization for fermions, Jordan and Wigner (1927/1928) observed that the algebra of a single pair of fermion creation and annihilation operators in quantum mechanics is closely related to the algebra of quaternions H. For the first time, here we exploit this fact to study nonlinear Bogolyubov-Valatin transformations (canonical transformations for fermions) for a single fermionic mode. By means of these transformations, a class of fermionic Hamiltonians in an external field is related to the standard Fermi oscillator.Comment: 6 pages REVTEX (v3: two paragraphs appended, minor stylistic changes, eq. (39) corrected, references [10]-[14], [36], [37], [41], [67]-[69] added; v4: few extensions, references [62], [63] added, final version to be published in J. Phys. A: Math. Gen.

EPR and ODMR defect control in AlN bulk crystals

The results of pulse electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR) and optically detected magnetic resonance (ODMR) are presented to show the electron structure of deep level defect color center in AlN single crystals such as a nitrogen vacancy in neutral charge state (VN 0) as well as a new type of point defect such as exchange-coupled pair of the nitrogen vacancies (VN-VN). Analyzing spin density distribution of an unpaired VN 0 electron on different ions of AlN crystalline lattice by means of high frequency ENDOR technique (94 GHz) give us a possibility to calculate hyperfine and quadrupole interactions (QI) with 27Al nuclei spins up to fourth coordinate sphere. Particularly data about quadrupole interactions allowed to estimate the fundamental parameter of AlN crystalline lattice in itself namely so called «crystalline field gradient» to be 4.9×1020V/m2 © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Enormously high concentrations of fluorescent nitrogen-vacancy centers fabricated by sintering of detonation nanodiamonds

High-pressure, high-temperature sintering of detonation nanodiamonds is used to fabricate material containing high concentrations of nitrogen-vacancy (NV) centers, without post or prior irradiation of the samples. The concentration of the NV centers in the sintered nanodiamond clusters is up to 10 4 ppm (1%) and is three orders of magnitude higher than any reported so far. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Body Fat Parameters, Glucose and Lipid Profiles, and Thyroid Hormone Levels in Schizophrenia Patients with or without Metabolic Syndrome

In this study, we aim to investigate associations between body fat parameters, glucose and lipid profiles, thyroid-stimulating hormone (TSH), and thyroid hormones (THs) levels in Tomsk-region schizophrenia patients depending upon the presence or absence of metabolic syndrome (MetS). A total of 156 psychiatric inpatients with schizophrenia who had been treated with antipsychotics for at least six months before entry were studied: 56 with and 100 without MetS. Reference groups consisted of general hospital inpatients with MetS and without schizophrenia (n = 35) and healthy individuals (n = 35). Statistical analyses were performed using the Mann-Whitney U-test, chi-square test, Spearman's rank correlation coefficient, multiple regression analyses, and descriptive statistics. Patients with schizophrenia and MetS had significantly higher levels of free triiodothyronine (FT3) and thyroxine (FT4) compared to schizophrenia patients without MetS (3.68 [3.25; 5.50] vs. 3.24 [2.81; 3.66], p = 0.0001, and 12.68 [10.73; 15.54] vs. 10.81 [9.76; 12.3], p = 0.0001, in pmol/L, respectively). FT3 maintained an association with MetS (p = 0.0001), sex (p = 0.0001), age (p = 0.022), and high-density lipoproteins (p = 0.033). FT4 maintained an association with MetS (p = 0.0001), sex (p = 0.001), age (p = 0.014), and glucose (p = 0.009). The data obtained showed body fat parameters, glucose and lipid profiles, and THs levels in Western-Siberian schizophrenia patients depending on MetS presence or absence

Evidence of exchange interaction of localized carriers and transition metals in diluted II-VI nanostructures: ODMR study

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Optically detected magnetic resonance study of (CdMn)Te/(CdMg)Te quantum wells allowed to reveal the formation of exchange-coupled complexes consisting of Mn ions and localized holes in quantum wells with excess hole concentration and the directional electron tunneling towards wider wells in multiple quantum well structures. The existence of a distribution of Mn-hole complexes that differ in a number of Mn ions interacting with a localized hole is justified. In colloidal cobalt doped ZnO nanocrystals, several nm in diameter, the interaction between the magnetic ions and the shallow donor electron in the confined system of ZnO quantum dots has been revealed. Direct evidence of interaction of Co ions with the interstitial Li shallow donor in the ZnO nanocrystal core and hyperfine coupling with 1H in the quantum dot shell have been demonstrated

Evidence of exchange interaction of localized carriers and transition metals in diluted II-VI nanostructures: ODMR study

Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimOptically detected magnetic resonance study of (CdMn)Te/(CdMg)Te quantum wells allowed to reveal the formation of exchange-coupled complexes consisting of Mn ions and localized holes in quantum wells with excess hole concentration and the directional electron tunneling towards wider wells in multiple quantum well structures. The existence of a distribution of Mn-hole complexes that differ in a number of Mn ions interacting with a localized hole is justified. In colloidal cobalt doped ZnO nanocrystals, several nm in diameter, the interaction between the magnetic ions and the shallow donor electron in the confined system of ZnO quantum dots has been revealed. Direct evidence of interaction of Co ions with the interstitial Li shallow donor in the ZnO nanocrystal core and hyperfine coupling with 1H in the quantum dot shell have been demonstrated. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Shallow Donors and Deep-Level Color Centers in Bulk AlN Crystals: EPR, ENDOR, ODMR and Optical Studies

The results of studies of shallow donors and deep-level color centers in bulk AlN crystals are presented. Two shallow donors (presumably oxygen located on the nitrogen site and carbon located on the aluminum site) are suggested to exhibit the DX-relaxation. Third shallow donor (presumably silicon on the Al site) shows the shallow donor behavior up to the room temperature and can be observed without light excitation at temperatures above 200 K. The values of the Bohr radius of the shallow donors are estimated. The structure of deep-level color centers (neutral nitrogen vacancy V N) in bulk AlN crystals is determined and analyzed by electron paramagnetic resonance, electron-nuclear double resonance, optical absorption and thermoluminescence induced by X-ray irradiation. Spin-dependent recombination processes in AlN crystals are studied by means of optically detected magnetic resonance. © 2013 Springer-Verlag Wien