| 1. |
- Artini, Cristina, et al.
(författare)
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Roadmap on thermoelectricity
- 2023
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Ingår i: Nanotechnology. - : IOP Publishing Ltd. - 0957-4484 .- 1361-6528. ; 34:29
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Tidskriftsartikel (refereegranskat)abstract
- The increasing energy demand and the ever more pressing need for clean technologies of energy conversion pose one of the most urgent and complicated issues of our age. Thermoelectricity, namely the direct conversion of waste heat into electricity, is a promising technique based on a long-standing physical phenomenon, which still has not fully developed its potential, mainly due to the low efficiency of the process. In order to improve the thermoelectric performance, a huge effort is being made by physicists, materials scientists and engineers, with the primary aims of better understanding the fundamental issues ruling the improvement of the thermoelectric figure of merit, and finally building the most efficient thermoelectric devices. In this Roadmap an overview is given about the most recent experimental and computational results obtained within the Italian research community on the optimization of composition and morphology of some thermoelectric materials, as well as on the design of thermoelectric and hybrid thermoelectric/photovoltaic devices.
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| 2. |
- Graziosi, Patrizio, et al.
(författare)
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Conditions for the growth of smooth La 0.7 Sr 0.3 MnO 3 thin films by pulsed electron ablation
- 2013
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 534, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- We report on the optimisation of the growth conditions of manganite La 0.7 Sr 0.3 MnO 3 thin films prepared by Channel Spark Ablation (CSA). CSA belongs to pulsed electron deposition methods and its energetic and deposition parameters are quite similar to those of pulsed laser deposition. The method has been already proven to provide manganite films with good magnetic properties, but the films were generally relatively rough (a few nm coarseness). Here we show that increasing the oxygen deposition pressure with respect to previously used regimes, reduces the surface roughness down to unit cell size while maintaining a robust magnetism. We analyse in detail the effect of other deposition parameters, like accelerating voltage, discharging energy, chamber pressure and substrate temperature and provide on this basis a set of optimal conditions for the growth of atomically flat films. The thicknesses for which atomically flat surface was achieved is as high as about 10-20 nm, corresponding to films with room temperature magnetism. We believe such magnetic layers represent appealing and suitable electrodes for various spintronic devices. © 2013 Elsevier B.V.
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| 3. |
- Li, Fenghong, et al.
(författare)
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Electronic structure and molecular orientation of pentacene thin films on ferromagnetic La0.7Sr0.3MnO3
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 81:20, s. 205415-1-205415-6
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Tidskriftsartikel (refereegranskat)abstract
- Pentacene thin films deposited on a ferromagnetic electrode, La0.7Sr0.3MnO3 (LSMO), have been studied using near-edge x-ray absorption fine structure (NEXAFS), ultraviolet photoemission spectroscopy (UPS), and atomic force microscopy (AFM). Here we present electronic structure and molecular orientation of pentacene thin film on LSMO. No evidence related to covalent bonding or significant charge transfer between pentacene and LSMO has been found in the NEXAFS or UPS results. UPS measurements suggest that the vertical ionization potential of pentacene on LSMO is 4.9 eV. Our results extracted from NEXAFS indicate that molecular long axis of pentacene stands on the LSMO substrate surface with a tilt angle of about 22 degrees +/- 2 degrees between the main molecular axis and the substrate surface normal. AFM images show the terracelike crystalline grain formed by stacking pentacene crystalline layers and a rough crystal-layer spacing of 14-15 angstrom. Findings deduced from UPS, NEXAFS, and AFM consistently demonstrate that pentacene stands on LSMO with a tilt angle.
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| 4. |
- Shi, Shengwei, et al.
(författare)
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11,11,12,12-Tetracyanonaphtho-2,6-quinodimethane in Contact with Ferromagnetic Electrodes for Organic Spintronics
- 2018
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Ingår i: Advanced Electronic Materials. - : WILEY. - 2199-160X. ; 4:7
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Tidskriftsartikel (refereegranskat)abstract
- Spinterface engineering has shown quite important roles in organic spintronics as it can improve spin injection or extraction. In this study, 11,11,12,12-tetracyanonaptho-2,6-quinodimethane (TNAP) is introduced as an interfacial layer for a prototype interface of Fe/TNAP. An element-specific investigation of the electronic and magnetic structures of Fe/TNAP system by use of near edge X-Ray absorption fine structure (NEXAFS) and X-ray magnetic circular dichroism (XMCD) is reported. Strong hybridization between TNAP and Fe and induced magnetization of N atoms in TNAP molecule are observed. XMCD sum rule analysis demonstrates that the adsorption of TNAP reduces the spin moment of Fe by 12%. In addition, induced magnetization in N K-edge of TNAP is also found with other commonly used ferromagnets in organic spintronics, such as La0.7Sr0.3MnO3 and permalloy, which makes TNAP a very promising molecule for spinterface engineering in organic spintronics.
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| 5. |
- Shi, Shengwei, et al.
(författare)
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Hybrid Interface States and Spin Polarization at Ferromagnetic Metal-Organic Heterojunctions : Interface Engineering for Efficient Spin Injection in Organic Spintronics
- 2014
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 24:30, s. 4812-4821
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Tidskriftsartikel (refereegranskat)abstract
- Ferromagnetic metal-organic semiconductor (FM-OSC) hybrid interfaces have been shown to play an important role for spin injection in organic spintronics. Here, 11,11,12,12-tetracyanonaptho-2,6-quinodimethane (TNAP) is introduced as an interfacial layer in Co-OSCs heterojunctions with an aim to tune the spin injection. The Co/TNAP interface is investigated by use of X-ray and ultraviolet photoelectron spectroscopy (XPS/UPS), near edge X-ray absorption fine structure (NEXAFS) and X-ray magnetic circular dichroism (XMCD). Hybrid interface states (HIS) are observed at Co/TNAP interfaces, resulting from chemical interactions between Co and TNAP. The energy level alignment at the Co/TNAP/OSCs interface is also obtained, and a reduction of the hole injection barrier is demonstrated. XMCD results confirm sizeable spin polarization at the Co/TNAP hybrid interface.
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