| 1. |
- Dokala, Ravi Kiran, et al.
(author)
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Elastic strain control of electronic structure, and magnetic properties of [Pr1-xCaxMnO3/SrTiO3](15) superlattices
- 2020
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In: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 127:17
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Journal article (peer-reviewed)abstract
- We report the growth, electronic structure, and in-plane magnetic properties of pulsed laser deposition grown 2D superlattice structures [Pr 0.7Ca 0.3MnO 3/SrTiO 3] 15 and [Pr 0.5Ca 0.5MnO 3/SrTiO 3] 15 on (001) oriented SrTiO 3 and LaAlO 3 single crystal substrates. The x-ray reflectivity measurements reveal well-defined interfaces between the manganite and titanate layers along with the existence of Kiessig fringes, providing the evidence for the smooth periodic superlattice structure. The reciprocal space mapping provides signature of tetragonal distortion in all the superlattices. The electronic structure determined from the x-ray photoelectron spectroscopy reveals divalent Sr and Ca, tetravalent Ti, and mixed valent Mn with a pronounce shift of binding energy peaks toward the higher energy side in the superlattices grown on (001) oriented LaAlO 3 as compared to those grown on SrTiO 3. These superlattices exhibit highly anisotropic ferromagnetic character. We used the law of approach to saturation to determine the anisotropy field (H K) and cubic anisotropy constant ( K 1) for all the investigated superlattices. This analysis yields the highest H K similar to 9kOe and K 1 similar to 8 x 10 5erg/cc for the [Pr 0.7Ca 0.3MnO 3/SrTiO 3] 15 superlattice system. Furthermore, significant enhancement of the overall magnetic moment and a decrease in T C ( < 100K) was observed in the case of LaAlO 3 grown superlattice, which indicates a substantial role of residual elastic strain on the magnetic ordering. Our results indicate that the strain induced elongation of MnO 6 octahedra leads to finite possibility of non-orthogonal overlapping of orbitals in the presence of large crystal field splitting of e g levels, which, in turn, causes suppression of the ferromagnetic double exchange interaction.
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| 2. |
- Das, Shantanu, et al.
(author)
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Individual Fairness in Feature-Based Pricing for Monopoly Markets
- 2022
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In: UAI 2022 - Proceedings of the 38th Conference on Uncertainty in Artificial Intelligence. ; PMLR 180, s. 486-795
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Conference paper (peer-reviewed)abstract
- We study fairness in the context of feature-based price discrimination in monopoly markets. We propose a new notion of individual fairness, namely, \alpha-fairness, which guarantees that individuals with similar features face similar prices. First, we study discrete valuation space and give an analytical solution for optimal fair feature-based pricing. We show that the cost of fair pricing is defined as the ratio of expected revenue in an optimal feature-based pricing to the expected revenue in an optimal fair feature-based pricing (CoF) can be arbitrarily large in general. When the revenue function is continuous and concave with respect to the prices, we show that one can achieve CoF strictly less than 2, irrespective of the model parameters. Finally, we provide an algorithm to compute fair feature-based pricing strategy that achieves this CoF.
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| 3. |
- Das, Sujit, et al.
(author)
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Vehicle lightweighting energy use impacts in U.S. light-duty vehicle fleet
- 2016
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In: Sustainable Materials and Technologies. - : Elsevier BV. - 2214-9937. ; 8, s. 5-13
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Journal article (peer-reviewed)abstract
- In this article, we estimate the potential energy benefits of lightweighting the light-duty vehicle fleet from both vehicle manufacturing and use perspectives using plausible lightweight vehicle designs involving several alternative lightweight materials, low- and high-end estimates of vehicle manufacturing energy, conventional and alternative powertrains, and two different market penetration scenarios for alternative powertrain light-duty vehicles at the fleet level. Cumulative life cycle energy savings (through 2050) across the nine material scenarios based on the conventional powertrain in the U.S. vehicle fleet range from - 29 to 94 billion GJ, with the greatest savings achieved by multi-material vehicles that select different lightweight materials to meet specific design purposes. Lightweighting alternative-powertrain vehicles could produce significant energy savings in the U.S. vehicle fleet, although their improved powertrain efficiencies lessen the energy savings opportunities for lightweighting. A maximum level of cumulative energy savings of lightweighting the U.S. light-duty vehicle through 2050 is estimated to be 66.1billion GJ under the conventional-vehicle dominated business-as-usual penetration scenario. (C) 2016 Elsevier B.V. All rights reserved.
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| 4. |
- Singh-Bhalla, Guneeta, et al.
(author)
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Unexpected termination switching and polarity compensation in LaAlO3/SrTiO3 heterostructures
- 2018
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In: Physical Review Materials. - : AMER PHYSICAL SOC. - 2475-9953. ; 2:11
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Journal article (peer-reviewed)abstract
- Polar crystals composed of charged ionic planes cannot exist in nature without acquiring surface changes to balance an ever-growing dipole. The necessary changes can manifest structurally or electronically as observed in semiconductors and ferroelectric materials through screening charges and/or domain wall formation. In the case of prototypical polar complex oxides such as the LaAlO3/SrTiO3 system the nature of screening charges for different interface terminations is not symmetric. Electron accumulation is observed near the LaAlO3/TiO2-SrTiO3 interface, while the LaAlO3/SrO-SrTiO3 stack is insulating. Here, we observe evidence for an asymmetry in the surface chemical termination for nominally stoichiometric LaAlO3 films in contact with the two different surface layers of SrTiO3 crystals, TiO2 and SrO. Using several element-specific probes, we find that the surface termination of LaAlO3 remains AlO2 irrespective of the starting termination of SrTiO3 substrate surface. We use a combination of cross-plane tunneling measurements and first-principles calculations to understand the effects of this unexpected termination on band alignments and polarity compensation of LaAlO3/SrTiO3 heterostructures. An asymmetry in LaAlO3 polarity compensation and resulting electronic properties will fundamentally limit atomic level control of oxide heterostructures.
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| 5. |
- Vijaybabu, T. R., et al.
(author)
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High Thermal Conductivity Polymer Composites Fabrication through Conventional and 3D Printing Processes: State-of-the-Art and Future Trends
- 2023
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In: Macromolecular materials and engineering. - : John Wiley & Sons. - 1438-7492 .- 1439-2054. ; 308:7
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Research review (peer-reviewed)abstract
- The lifespan and the performance of flexible electronic devices and components are affected by the large accumulation of heat, and this problem must be addressed by thermally conductive polymer composite films. Therefore, the need for the development of high thermal conductivity nanocomposites has a strong role in various applications. In this article, the effect of different particle reinforcements such as single and hybrid form, coated and uncoated particles, and chemically treated particles on the thermal conductivity of various polymers are reviewed and the mechanism behind the improvement of the required properties are discussed. Furthermore, the role of manufacturing processes such as injection molding, compression molding, and 3D printing techniques in the production of high thermal conductivity polymer composites is detailed. Finally, the potential for future research is discussed, which can help researchers to work on the thermal properties enhancement for polymeric materials.
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