| 1. |
- Niarchos, D., et al.
(author)
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Toward Rare-Earth-Free Permanent Magnets : A Combinatorial Approach Exploiting the Possibilities of Modeling, Shape Anisotropy in Elongated Nanoparticles, and Combinatorial Thin-Film Approach
- 2015
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In: JOM. - : Springer Science and Business Media LLC. - 1047-4838 .- 1543-1851. ; 67:6, s. 1318-1328
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Journal article (peer-reviewed)abstract
- The objective of the rare-earth free permanent magnets (REFREEPM) project is to develop a new generation of high-performance permanent magnets (PMs) without rare earths. Our approach is based on modeling using a combinatorial approach together with micromagnetic modeling and the realization of the modeled systems (I) by using a novel production of high-aspect-ratio (> 5) nanostructrures (nanowires, nanorods, and nanoflakes) by exploiting the magnetic shape anisotropy of the constituents that can be produced via chemical nanosynthesis polyol process or electrodeposition, which can be consolidated with novel processes for a new generation of rare-earth free PMs with energy product in the range of 60 kJ/m(3) < (BH)max < 160 kJ/m(3) at room temperature, and (II) by using a high-throughput thin-film synthesis and high-throughput characterization approach to identify promising candidate materials that can be stabilized in a tetragonal or hexagonal structure by epitaxial growth on selected substrates, under various conditions of pressure, stoichiometry, and temperature. In this article, we report the progress so far in selected phases.
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| 2. |
- Papawassiliou, Wassilios, 1991-, et al.
(author)
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Detection of Weyl fermions and the metal to Weyl-semimetal phase transition in WTe2via broadband high resolution NMR
- 2022
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In: Physical Review Research. - 2643-1564. ; 4:3
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Journal article (peer-reviewed)abstract
- Weyl fermions (WFs) in the type-II Weyl semimetal (WSM) WTe2 are difficult to resolve experimentally because the Weyl bands disperse in an extremely narrow region of the (E−k) space. Here, by using DFT-assisted high-resolution 125Te solid-state nuclear magnetic resonance (ssNMR) in the temperature range 50–700 K, we succeeded in detecting low energy WF excitations and monitoring their evolution with temperature. Remarkably, WFs are observed to emerge at T∼120 K, while at lower temperatures WTe2 behaves as a trivial metal. This intriguing phenomenon is induced by the rapid raise of the Fermi level upon heating, which crosses the Weyl bands only for T>120 K. The abrupt change of the NMR parameters at this temperature is signature of a topological Lifshitz transition instead of a cursive energy-bands crossing.
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