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A microscopic control over the origin and dynamics of localised spin centres in lower dimensional solids turns out to be a key factor for next generation spintronics and quantum technologies. With the help of low temperature electron paramagnetic resonance (EPR) measurements, supported by the first-principles calculations within density functional theory (DFT) formulation, we found the origin of different high-spin paramagnetic intrinsic charge-centres, Mo3+(4d3) and Mo2+(4d4) present in the nano-crystalline sulfur deficit hexagonal molybdenum disulfide (2H-MoS_(2-x)), against the established notion of spin-1/2 , Mo5+ centres. A critical strain generated in the nano-structured 2H-MoS_(2-x) was found to be very crucial for spin-localization in this layered material. Indeed, computationally effective proposition of the PBE+U exchange-correlations within DFT including D3-dispersion corrections found to be more viable than expensive higher rung of exchange-correlation functionals, explored earlier. It is also found that the oxygen vacancy of the reduced oxide phase, embedded in 2H-MoS_(2-x) host lattice, has the longest relaxation times. Moreover, the temperature dependence of spin-lattice relaxation measurements reveals a direct process for interstitial spin centres and a Raman process for both sulfur and oxygen vacancy sites. We expect such observation would be a valuable pillar for better understanding of the next generation quantum technologies and device applications., Comment: This manuscript has 38 pages in single column and 7 figures. Supplementary information is not attached

Semi-supervised learning (SSL) uses unlabeled data during training to learn better models. Previous studies on SSL for medical image segmentation focused mostly on improving model generalization to unseen data. In some applications, however, our primary interest is not generalization but to obtain optimal predictions on a specific unlabeled database that is fully available during model development. Examples include population studies for extracting imaging phenotypes. This work investigates an often overlooked aspect of SSL, transduction. It focuses on the quality of predictions made on the unlabeled data of interest when they are included for optimization during training, rather than improving generalization. We focus on the self-training framework and explore its potential for transduction. We analyze it through the lens of Information Gain and reveal that learning benefits from the use of calibrated or under-confident models. Our extensive experiments on a large MRI database for multi-class segmentation of traumatic brain lesions shows promising results when comparing transductive with inductive predictions. We believe this study will inspire further research on transductive learning, a well-suited paradigm for medical image analysis., Comment: Published at Domain Adaptation and Representation Transfer (DART) wshop at MICCAI 2021. This version improves methods' names and adds 1 experiment in Tab.3a

The current family of experimentally realized two-dimensional magnetic materials consist of 3$d$ transition metals with very weak spin-orbit coupling. In contrast, we report a new platform in a chemically bonded and layered 4$d$ oxide, with strong electron correlations and competing spin-orbit coupling. We synthesize ultra-thin sheets of SrRu$_2$O$_6$ using scalable liquid exfoliation. These exfoliated sheets are characterized by complementary experimental and theoretical techniques. The thickness of the nano-sheets varies between three to five monolayers, and within the first-principles calculations, we show that antiferromagnetism survives in these ultra-thin layers. Experimental data suggest that exfoliation occurs from the planes perpendicular to the $c$-axis as the intervening hexagonal Sr-lattice separates the two-dimensional magnetic honeycomb Ru-layers. The high-resolution transmission electron microscope images indicate that the average inter-atomic spacing between the Ru-layers is slightly reduced, which agrees with the present calculations. The signatures of rotational stacking of the nanosheets are also observed. Such new two-dimensional platform offers enormous possibilities to explore emergent properties that appear due to the interplay between magnetism, strong correlations and spin-orbit coupling. Moreover, these effects can be further tuned as a function of layer thickness.

The structural and electronic properties of bulk, monolayer and ultrathin films of V$_2$O$_5$ and MoO$_3$ layered oxides have been studied with first-principles density functional theory calculations including Van der Waals dispersion corrections. Specific DFT+U functionals have been tested in order to properly reproduce geometry, band-gap, static dielectric constant, and formational enthalpies of the two materials. The mono-, and multi-layers are cleaved along the <001> and <010> stable crystallographic orientations for V2O5 and MoO3, respectively. At least three layers are needed for both materials in order to recover bulk-like properties. Spin-orbit effects have been incorporated in our prediction, but they show marginal effects., Comment: Need further upgrade of results

Using first-principles density functional theory (DFT), we studied the issue of water incorporation in iron bearing wadsleyite (Mg$_2$SiO$_4$)mineral at transition zone pressures and temperature under varying conditions of vacancy concentration and oxygen fugacity. We have considered the effect of varying vacancy concentration by considering single and double vacancy. The affect of varying oxygen fugacity has been modelled through varying ratio of ferric and ferrous ions in the cell. Our first-principles calculations have confirmed that about 30% of the Fe$^{3+}$ can be found at the Si tetrahedral site, which is in accordance with the previous experimental observation by Bolfan-Casanova et al. [2012]. Using different structures of Fe bearing wadsleyite, representing vacancy concentration and oxidizing condition, we calculated elastic properties, such as bulk and shear moduli, phase and shear wave velocity, as a function of pressure and temperature. By comparison of our theoretical prediction with the Preliminary Reference Earth Model (PREM) data, we conclude that the water content of the transition zone decreases with increasing depth, corroborating the previously proposed theories on mantle convection [Bercovici and Karato, 2003]., Comment: one author not agree with results part

The challenge of finding an absolute reference energy from first-principles simulations to realigning semiconductor's valence band-top and conduction band-bottom, a theoretical methodology is proposed based on plane-wave calculations as implemented within state-of-art density functional theory. We have studied some of inorganic binary semiconductors, including both oxides and non-oxides, as for example rutile- and anatase TiO2, wurtzite ZnO, rutile SnO2, blende phase of GaP, GaAs, InP, ZnTe, CdS, CdSe, and SiC, those are well known and qualitatively important for photoelectrochemical, optoelectronic device applications in their standalone and/or heterostructure morphologies. The calculated band-edges of these well known semiconductors are realigned with respect to our proposed absolute vacuum reference energy, which is defined with our proposed corrections and compared to their available experimental values from flat-band measurement. The prediction is reasonably well agreed with known experimental flat-band measured data. Our estimated mean absolute error bar for these set of eleven compounds is ~ 0.17 eV, closer to the known experimental limit 0.10-0.20 eV., Comment: 21 Pages Manuscript, with 4 Figures and 2 Tables. SI report 12 Pages