Electron Spin Resonance Method Research Articles

Creation of optically addressable spin centers in hexagonal boron nitride by proton irradiation

The possibility of creating defects with spin-dependent fluorescence in a Van der Waals material, hexagonal boron nitride (hBN), by irradiating the latter with high-energy protons (EP=15 MeV) has been studied. Using micro-photoluminescence and electron paramagnetic resonance methods it was shown that such irradiation leads to the creation of boron vacancies in the negative charge state (V-B-centers). The ground spin triplet (S=1) state of these defects demonstrates an optically induced inverse population. Keywords: electron paramagnetic resonance, micro-photoluminescence, hexagonal boron nitride, boron vacancy.

The nitric oxide production in tissues of 7- and 16-week-old rats under mobility restriction

The electron paramagnetic resonance method was used to study the intensity of nitric oxide production by analyzing the amount of NO-containing paramagnetic complexes in the heart, liver, and spinal cord tissues of 7- and 16-week-old rats growing under restricted mobility conditions. Nitric oxide production was assessed by the intensity of the EPR signal belonging to the (DETC)2-Fe2+NO complex. The results obtained show that growth under conditions of restricted motility leads to an increase in NO production in all organs under study, with the greatest increase observed in 7-week-old rats. Keywords: nitric oxide, heart, liver, spinal cord, electron paramagnetic resonance.

Продукция оксида азота в тканях крыс 7- и 16-недельного возраста при ограничении подвижности

The electron paramagnetic resonance method was used to study the intensity of nitric oxide production by analyzing the amount of NO-containing paramagnetic complexes in the heart, liver, and spinal cord tissues of 7- and 16-week-old rats growing under restricted mobility conditions. Nitric oxide production was assessed by the intensity of the EPR signal belonging to the (DETC)2-Fe2+-NO complex. The results obtained show that growth under conditions of restricted motility leads to an increase in NO production in all organs under study, with the greatest increase observed in 7-week-old rats.

Создание оптически адресуемых спиновых центров в гексагональном нитриде бора путем облучения протонами

The possibility of creating defects with spin-dependent fluorescence in a Van der Waals material, hexagonal boron nitride (hBN), by irradiating the latter with high-energy protons (EP = 15 MeV) has been studied. Using micro-photoluminescence and electron paramagnetic resonance methods it was shown that such irradiation leads to the creation of boron vacancies in the negative charge state (V-B^- -centers). The ground spin triplet (S = 1) state of these defects demonstrates an optically induced inverse population.

The Tooth Enamel from Köşk Höyük, Niğde,Turkey Determination of the Physical Properties and Estimation of Radiation Dose Using Electron Spin Resonance (ESR) Method

The Tooth Enamel from Köşk Höyük, Niğde,Turkey Determination of the Physical Properties and Estimation of Radiation Dose Using Electron Spin Resonance (ESR) Method

Study on Chemical Constituents and Antioxidant Activity of the Flat-European Hybrid Hazelnut (C. heterophylla Fisch. × C. avellana L.) Oil

Hazelnut oil, extracted from hazelnuts, can be used as a functional food with many nutritional benefits. To completely assess its chemical constituents in hazelnut oil, one main cultivar of a flat-European hybrid hazelnut (C. heterophylla Fisch. × C. avellana L.) cv. ‘Dawei’ was taken as the material, and a new optimized silyl-etherification derivatization was established by being followed with Gas chromatography-mass spectrometry (GC-MS). Meanwhile, an electron spin resonance (ESR) method was used to elucidate the scavenging capacity of free radicals. In result, the filbertone (exclusive marker), 16 fatty acids (8 saturated and 8 unsaturated), 4 sterols and 5 other components were identified at once. Furthermore, hybrid hazelnut oil, filbertone and two sterols that contained in hazelnut oil were used to test the scavenge free radical activities. The results showed that the hybrid hazelnut oil expressed meaningful IC50 values (DPPH: 66.39, hydroxyl: 66.64, alkyl: 118.82 and O2¯: 75.38 μg/mL). In conclusion, this study selected an effective derivatization method for the chemical constituents detection, and provided detailed data, which laid an experimental foundation for quality control of a hybrid hazelnut oil. In addition, the free radical scavenging activity was observed, which provided a basis for the development of antioxidant products in hybrid hazelnut oil.

Metabotropic glutamate receptors and nitric oxide in dopaminergic neurotoxicity.

Dopaminergic neurotoxicity is characterized by damage and death of dopaminergic neurons. Parkinson's disease (PD) is a neurodegenerative disorder that primarily involves the loss of dopaminergic neurons in the substantia nigra. Therefore, the study of the mechanisms, as well as the search for new targets for the prevention and treatment of neurodegenerative diseases, is an important focus of modern neuroscience. PD is primarily caused by dysfunction of dopaminergic neurons; however, other neurotransmitter systems are also involved. Research reports have indicated that the glutamatergic system is involved in different pathological conditions, including dopaminergic neurotoxicity. Over the last two decades, the important functional interplay between dopaminergic and glutamatergic systems has stimulated interest in the possible role of metabotropic glutamate receptors (mGluRs) in the development of extrapyramidal disorders. However, the specific mechanisms driving these processes are presently unclear. The participation of the universal neuronal messenger nitric oxide (NO) in the mechanisms of dopaminergic neurotoxicity has attracted increased attention. The current paper aims to review the involvement of mGluRs and the contribution of NO to dopaminergic neurotoxicity. More precisely, we focused on studies conducted on the rotenone-induced PD model. This review is also an outline of our own results obtained using the method of electron paramagnetic resonance, which allows quantitation of NO radicals in brain structures.

Optical and Structural Properties of Mn4+‐Activated (ZnxMg1–x)2TiO4 Red Phosphors

A report on optical and structural investigations of Mn4+‐activated (ZnxMg1–x)2TiO4 red phosphors by X‐ray diffraction, photoluminescence (PL), and electron paramagnetic resonance methods is provided. The phosphors of Mg2TiO4, Zn2TiO4 and solid solutions (ZnxMg1–x)2TiO4 (x = 0.25, 0.50, 0.75) with manganese content of 0.1 mol% are synthesized at temperatures in the range of 800–1200 °C via solid state reaction. Formation of solid solutions of inverse spinel structure demonstrates the features similar to both the Mg2TiO4 and Zn2TiO4, i.e., decomposition of the (Zn,Mg)2TiO4 on the (Zn,Mg)TiO3 and MgO and separation of the secondary ZnO phase, respectively. These processes depend on the composition of solid solution and sintering temperature, and for some regimes, the single‐phase phosphor can be obtained. The largest intensity of Mn4+ red PL is found in the Mn‐doped (Zn0.25Mg0.75)2TiO4 phosphor sintered at 1100 °C and it is 2 times larger than those in similar Mn4+‐activated Mg2TiO4 phosphor. The differences in the PL intensity of the phosphors of solid solutions are explained by different PL thermal quenching as well as by competing processes of Mn incorporation in +2 and +4 charge states in zinc–magnesium titanate crystal lattice.

S3 State Models of Nature's Water Oxidizing Complex: Analysis of Bonding and Magnetic Exchange Pathways, Assessment of Experimental Electron Paramagnetic Resonance Data, and Implications for the Water Oxidation Mechanism.

Broken symmetry density functional theory (BS-DFT) calculations on large models of Nature's water oxidizing complex (WOC) are used to investigate the electronic structure and associated magnetic interactions of this key intermediate state. The electronic origins of the ferromagnetic and antiferromagnetic couplings between neighboring Mn ions are investigated and illustrated by using corresponding orbital transformations. Protonation of the O4 and/or O6 atoms leads to large variation in the distribution of spin around the complex with associated changes in its magnetic resonance properties. Models for Sr2+ exchange and methanol addition indicate minor perturbations reflected in slightly altered spin projection coefficients for the Mn1 and Mn2 ions. These are shown to account for the observed changes observed experimentally via electron paramagnetic resonance methods and suggest a reinterpretation of the experimental findings. By comparison with experimental determinations, we show that the spin projections and resulting calculated 55Mn hyperfine couplings support the open cubane form of an oxo (O5)-hydroxo (O6) cluster in all cases with no need to invoke a closed cubane intermediate. The implications of these findings for the water oxidation mechanism are discussed.

A novel nonapeptide SSDAFFPFR from Antarctic krill exerts a protective effect on PC12 cells through the BCL-XL/Bax/Caspase-3/p53 signaling pathway

This study aims to investigate the protective effect on PC12 cells of Ser-Ser-Asp-Ala-Phe-Phe-Pro-Phe-Arg(SSDAFFPFR) and Ser-Asn-Val-Phe-Asp-Met-Phe (SNVFDMF) derived from Antarctic krill and the related signaling pathways involved in the inhibition of oxidative stress. Peptide sequences of the antioxidant component in the hydrolysates of Antarctic krill were identified by Nano-HPLC- MS/MS, then the bioactivity was predicted by in silico analysis. Results showed that SSDAFFPFR and SNVFDMF showed the highest activity with a PeptideRanker score of 0.97 and 0.89, respectively, and both contained serine and phenylalanine related to the antioxidant activity. Based on Electron paramagnetic resonance (EPR) method, SSDAFFPFR exhibited a higher DPPH radical scavenging rate than SNVFDMF (71.88 ± 4.01% vs 34.57 ± 2.38%), due to the presence of hydroxyl, amino, and carboxyl groups at its C and N terminals as well as the branched-chain of SSDAFFPFR peptide. In addition, SSDAFFPFR significantly suppressed the decrease of SOD activity and decreased ROS content induced by scopolamine in PC12 cells, as well as inhibited the expression of Bax, Caspase-3 and p53 and promoted the expression of BCL-XL, thereby protecting PC12 cells from the effects of oxidative stress. Thus the Antarctic krill peptide SSDAFFPFR showed its protective effect on PC12 cells through the BCL-XL/Bax/Caspase-3/p53 pathway.

Detection of sub-nanotesla magnetic fields by linewidth narrowing in high-density nitrogen vacancy magnetometry with pulsed ESR method

Contrast and linewidth, which depend on the microwave (MW) and light powers, are critical for optimizing magnetometer sensitivity based on high-density nitrogen vacancy (NV) centers in diamond. Therefore, the tradeoff between laser and MW powers can be adjusted to optimize the contrast and linewidth extracted from the magnetic resonance. In this paper, we developed a pulsed electron spin resonance (ESR) measurement to enhance the magnetic field sensitivity of an NV magnetic sensor with high-density NV centers in diamond by narrowing the linewidth while keeping the contrast almost constant. Furthermore, for a wide range of experimental settings of MW and light powers in the continuous-wave (CW) method, the contrast and linewidth always increase with increasing MW power. However, by using a simple pulsed ESR sequence based on the repetitive excitation of NV centers, linewidth broadening under relatively high MW power is avoided. The magnetic field sensitivity reaches less than by eliminating the power broadening of the linewidth of ESR, which is one third of that achieved using CW measurements. Finally, the possibility of enhancing magnetic-field sensitivity utilizing the light-narrowing effect is discussed.

First Chronological Constraints for the High Terraces of the Upper Ebro Catchment

The Cenozoic sedimentary basins in the Iberian Peninsula show a change from long-term basin infill to incision, a transition that indicates a period of major drainage reorganization that culminated in the throughflow of the networks to the Atlantic and Mediterranean oceans. Both the cause of the transition from aggradation to degradation and the linkages to tectonic, climatic, and geomorphic events hinge on the chronology of the fluvial network incision and excavation of the basin’s sedimentary fills. In this paper, we describe the first chronologic data on the highest fluvial terraces of the upper area of the Ebro River, one of the largest fluvial systems in the Iberian Peninsula, to determine the onset of incision and excavation in the basin. For this purpose, we combine electron spin resonance (ESR) and paleomagnetism methods to date strath terraces found at 140, 90, and 85 m above the current river level. Our results show ages of ca. 1.2 and 1.5 Ma for the uppermost river terraces in the upper Ebro catchment, constraining the minimum age of the entrenchment of the upper Ebro River.

Hybrid Cu-Fe/ZSM-5 Catalyst Prepared by Liquid Ion-Exchange for NOx Removal by NH3-SCR Process

A series of Cu/ZSM-5, Fe/ZSM-5, and Cu-Fe/ZSM-5 catalysts (Si/Al in ZSM-5 = 25) were prepared by different metal loadings using the liquid ion-exchange method. Several characterization methods were conducted to explore the effects of metals on the physical and chemical properties of catalysts. Meanwhile, the electron paramagnetic resonance method is also used to assess the copper and/or iron elements’ coordination and valence state at intersections or in channels of ZSM-5. The metal-loading effects of all catalysts on the catalytic activities were studied for the removal of NOx in a fixed-bed flow reactor using selective catalytic reduction with ammonia (NH3-SCR). The results showed that the iron’s addition could markedly broaden the operation temperature range of the Cu/ZSM-5 catalyst for NH3-SCR between 200 and 550°C due to the presence of more isolated Cu2+ ions as well as additional oligomeric Fe3+ active sites and FexOy oligomeric species. This paper gives a facile and straightforward way to synthesize the practical-promising catalyst applied in NH3-SCR technology to control NOx emissions.

Mechanism and impacts of inorganic ion addition on photocatalytic degradation of triclosan catalyzed by heterostructured Bi7O9I3/Bi

BackgroundTriclosan, a broad-spectrum bacteriostatic germicide, is widely used in daily life. Traditional methods for removal of triclosan however suffer from possible secondary pollution. Photocatalytic technology is considered one of the most promising methods because of its low cost and high efficiencies, which removes pollutants through direct utilization of solar energy. MethodsHere, a heterostructured composite photocatalyst Bi7O9I3/Bi was prepared through an in situ reduction method for photocatalytic degradation of triclosan, with the degradation mechanism investigated with a free radical trapping experiment and an electron spin resonance (ESR) method. Furthermore, the effects of the presence of inorganic ions on the degradation efficiencies were investigated. FindingsCompared with Bi7O9I3, the degradation efficiency of Bi7O9I3/Bi on triclosan was significantly improved. This is mainly attributed to the formation of Bi nanoparticles on the surface of Bi7O9I3, which effectively promotes the light absorption through surface plasmon effects of Bi and separation of photo-generated electron-hole pairs through band structure modulation, thereby greatly improving the photocatalytic performances. The photo-generated electrons (e−) and superoxide radicals (·O2−) were found to be the main active species for triclosan degradation. Furthermore, the presence of NO3−, SO42- and Cl− all hamper the photodegradation of triclosan, whereas HCO3−, Ca2+ and Mg2+ inhibit or promote it depending on their concentrations.

Study on the Chemical Structures and Free Radical Scavenging Ability of Anthraquinones and Its c-Glycosides from Rumexjaponicus Houtt.

Rumex japonicus Houtt. (RJH) is a kind of Traditional Chinese Medicine (TCM) widely used in the treatment of serious skin diseases such as psoriasis. To further explore its bioactive components, the five-year root of RJH was used, the nuclear magnetic resonance (NMR) technique was employed with DMSO-d6 solvent for chemical structures, the scavenging capacity of the free radicals (DPPH, alkyl, –OH, and ˙O−2) was evaluated by electron spin resonance (ESR) method. In the results, seven compounds that were wholly characterized as anthraquinones (1 and 2), its c-glycosides (4–7), and flavonoid glycoside (3) especially for the hydrogen atoms from –OH groups located at phenol rings and glucose moieties. The compound 4 and 5 showed the significant bioac-tivity with the IC50 values (DPPH: 23.34 and 23.25 μM; alkyl: 20.27 and 20.15 μM; –OH: 26.03 and 25.50 μM; and ˙O−2: 14.69 and 14.68 μM, respectively). In conclusion, the DMSO-d6 solvent could make active protons be expressed clearly for accurate assignments. The compounds 4 and 5 could be suggested to be applied for potential candidates for related drugs.

−22-Fold of 1H signal enhancement in-situ low-field liquid NMR using nanodiamond as polarizer of overhauser dynamic nuclear polarization

Nanodiamond (ND) polarizer can be used for dynamic nuclear polarization (DNP), owing to unpaired electrons provided by surface defects. However, 1H enhancement via Overhauser DNP (ODNP) using ND in-situ liquid has been found much smaller than traditional radicals. Herein, we study the surface properties of ND using electron spin resonance (ESR) and Raman methods firstly. Then the enhancement of 1H ODNP is explored using ND as polarizer with different nanoparticle sizes and concentrations at home-built 0.06 T DNP spectrometer. The surface of ND with the size of 30 nm is further modification via high temperature air oxidized and the enhancement was measured. The results show that nanoparticle sizes and Raman peak intensity ratio of sp2/sp3 hybridization are approximate negative correlation and positive correlation to enhancement, respectively. Furthermore, there is no significant enhancement in the oxidation group, and a −22.5-fold 1H ODNP enhancement is achieved in-situ liquid at room temperature, which demonstrate the ND can be used as an efficient enhancer. We expect ND to play a greater role in biomedical research, especially for multimodal imaging with improving the performance of ND surface.

(Invited) Vibronic Effect of Donor-Acceptor Interaction Determines Fate of Mutiexciton Spins Generated By Singlet Fission

Singlet fission (SF) is expected to exceed the Shockley–Queisser theoretical limit with power conversion efficiencies (PCE) ~33 % of single junction organic solar cells (OSC) because two separated triplet excitons (T+T) can be produced from one excited singlet state (S1S0) sharing its excitation energy with a neighboring ground-state chromophore. The intramolecular SF (iSF) dynamics have widely been studied using the transient absorption spectroscopic methods together with theoretical modeling taking into account the vibronic effects in the ultrafast regimes. The correlated intermolecular triplet pair 1(TT) generated with the singlet character is known to be converted to the quintet (Q) state as 5(TT). These TT pairs separate into individual triplets as the T+T state. In the previous study, we reported the iSF dynamics and subsequent separations to T+T in the pentacene dimers (PcD) bridged by a phenylene at ortho and meta positions by a combination of the ultrafast transient absorption spectroscopy and the time-resolved electron paramagnetic resonance (TREPR) method.1 Before the spin-conversions to the 5(TT) state, the initially populated 1(TT) is strongly coupled in the four unpaired spins of the two triplet excitons, i.e. the entangled spin-state by large spin-spin exchange coupling (J) with the large orbital overlap produced at femtoseconds regions. The modulations of the J-couplings are thought to be essential for the 1(TT) -> 5(TT) conversions. In an iSF system, we interpreted that the quintet ESPs were caused by the anisotropic spin conversions due to singlet-quintet spin-relaxations to the five sublevels at m S = +2, +1, 0, -1 and -2 in accordance with the anisotropy of the ZFS coupling which is highly dependent on the relative orientation of one triplet exciton (TB) with respect to the other triplet (TA) in the TATB multiexciton.2 Internal fluctuations in the J-coupling were concluded to be crucial on the quintet generations. Moreover, we reported the treatment of the EPR transitions in the weakly coupled T+T states in the framework of the spin-correlated triplet pair (SCTP) for the very weak exchange coupling including the superpositions of the nine basis functions of 5(TT) - 3(TT) - 1(TT), as treated in the spin-correlated radical pair model. 3,4 The above pioneering interpretations of the ESP mechanisms may pave a new avenue to clarify how the molecular conformations and their motions drive the spin-conversions and the ultimate T+T generations, both of which are essential but unknown for the photon-to-energy conversion process. In particular, because the J-coupling is anticipated to be sensitive to the TATB conformations, it is expected that the specific molecular motions or phonon modes may play roles for the ultimate T+T de-coupling, as the vibronic effects. So far, details of the TATB geometries, the vibration modes and frequencies, and the electronic couplings are unresolved in the iSF systems for generating the quintet multiexcitons and the subsequent T+T dissociations.We have characterized the molecular geometries, conformation dynamics and J-couplings of the intramolecular multiexcitons after the photoinduced iSF with the proposal of the density matrix analysis of ESP observed by the TREPR method. It is concluded that the J-coupling is determined by the donor-acceptor electronic coupling in the multiexciton and that terahertz TA-TB conformation dynamics plays a significant role for generating the quintet multiexcitons and for the individual T+T states caused by the J-fluctuation in the covalently linked systems.4 Sakai, H.; Inaya, R.; Nagashima, H.; Nakamura, S.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T., J. Phys. Chem. Lett. 2018, 9, 3354-3360.Matsui, Y.; Kawaoka, S.; Nagashima, H.; Nakagawa, T.; Okamura, N.; Ogaki, T.; Ohta, E.; Akimoto, S.; Sato-Tomita, A.; Yagi, S., et al., J. Phys. Chem. C 2019, 123, 18813-18823.Matsuda, S.; Oyama, S.; Kobori, Y., Chem. Sci. 2020, 11, 2934-2942.Kobori, Y.; Fuki, M.; Nakamura,; S. Hasobe, T. J. Phys. Chem. B 2020, 124, 9411–9419.

Jellyfish-like few-layer graphene nanoflakes: high paramagnetic response alongside increased interlayer interaction

Abstract Jellyfish-like graphene nanoflakes (GNF), prepared by hydrocarbon pyrolysis, are studied with electron paramagnetic resonance (EPR) method. The results are supported by X-ray photoelectron spectroscopy (XPS) data. Oxidized (GNFox) and N-doped oxidized (N-GNFox) flakes exhibit an extremely high EPR response associated with a large interlayer interaction which is caused by the structure of nanoflakes and layer edges reached by oxygen. The GNFox and N-GNFox provide the localized and mobile paramagnetic centers which are silent in the pristine (GNF p ) and N-doped (N-GNF) samples. The change in the relative intensity of the line corresponding to delocalized electrons is parallel with the number of radicals in the quaternary N-group. The environment of localized and mobile electrons is different. The results can be important in GNF synthesis and for explanation of their features in applications, especially, in devices with high sensitivity to weak electromagnetic field.

Relaxation processes and high-field coherent spin manipulation in color center ensembles in 6 H -SiC

Coherent spin manipulations of spin-$\frac{3}{2}$ color center ensembles in 6H-SiC crystal have been studied in high magnetic fields using methods of pulsed electron paramagnetic resonance, Rabi oscillations, and pulsed electron-electron double resonance under optical alignment conditions of the spin level populations. Rabi oscillation experiments show room temperature coherent control of these spin-$\frac{3}{2}$ color center ensembles in strong magnetic fields. A sharp decrease of the spin-lattice relaxation time ${T}_{1}$, \ensuremath{\sim}40 times, was observed in 6H-SiC at magnetic field of \ensuremath{\sim}3.5 T with increasing temperature from 100 to 300 K, while the spin-spin relaxation time ${T}_{2}$ is only shortened by \ensuremath{\sim}1.3 times. With an increase in the magnetic field, the times ${T}_{1}$ and ${T}_{2}$ were shown to decrease. The relaxation time ${T}_{1}$ in the case of magnetic field directed along the axis of the spin-$\frac{3}{2}$ center is \ensuremath{\sim}2 times longer than ${T}_{1}$ in magnetic field perpendicular to this axis. Relaxation times of the spin center in crystal grown with a reduced concentration of an isotope $^{29}\mathrm{Si}$ are significantly longer than crystal, with the natural content of isotopes. With a decrease in the $^{29}\mathrm{Si}$ content in our experiments by a factor of \ensuremath{\sim}5, the effective nuclear spin bath in SiC is reduced by a factor of \ensuremath{\sim}2. In a zero magnetic field resonance, transitions are allowed as magnetic dipole transitions with frequency ${\ensuremath{\omega}}_{0}$ which correspond to the zero-field splitting. In zero magnetic field and in fixed magnetic fields, the Rabi frequency was shown, using so-called ``Feynman-Vernon-Hellwarth transformation,'' to be ${\ensuremath{\omega}}_{R}=|\ensuremath{\gamma}|{B}_{1}$. In pulsed electron-electron double resonance experiments, a change in the intensity of the electron spin echo signal corresponding to one of the spin-allowed fine structure transitions is recorded depending on the sweep of the second frequency. The experiments show the possibility to coherently detect the optical spin alignment between ${M}_{S}=\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ via optically pumped silent ${M}_{S}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ sublevels of the spin-$\frac{3}{2}$ color centers, including a detection of Rabi oscillations.

Magnetic Properties of Li3V2(PO4)3/Li3PO4 Composite

Here, we present the investigation of the magnetic properties of Li3V2(PO4)3/Li3PO4 composites, which can be potentially used as a cathode material in lithium-ion batteries. Li3V2(PO4)3/Li3PO4 was synthesized by the thermal hydrolysis method and has a granular mesoporous structure. Magnetic properties of the composite were investigated using magnetometry and electron spin resonance methods. Based on magnetization measurements, the simultaneous existence of the paramagnetic phase with antiferromagnetic interactions between spins of V3+ ions and magnetically correlated regions was suggested. Most probably, magnetically correlated regions were formed due to anti-site defects and the presence of V4+ ions that was directly confirmed by electron spin resonance measurements.