| 1. |
- Witteveen, Catherine, et al.
(author)
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Synthesis and anisotropic magnetic properties of LiCrTe2 single crystals with a triangular-lattice antiferromagnetic structure
- 2023
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In: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:3
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Journal article (peer-reviewed)abstract
- We report on the synthesis of LiCrTe2 single crystals and on their anisotropic magnetic properties. We have obtained these single crystals by employing a Te/Li-flux synthesis method. We find LiCrTe2 to crystallize in a TlCdS2 -type structure with cell parameters of a = 3.9512(5) angstrom and c = 6.6196(7) angstrom at T = 175 K. The content of lithium in these crystals was determined to be neary stoichiometric by means of neutron diffraction. We find a pronounced magnetic transition at T-N(ab) = 144 K and T-N
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| 2. |
- Zhang, Xiaofu, et al.
(author)
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Suppression of the transition to superconductivity in crystal/glass high-entropy alloy nanocomposites
- 2022
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In: Communications Physics. - : NATURE PORTFOLIO. - 2399-3650. ; 5:1
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Journal article (peer-reviewed)abstract
- High entropy alloys are multielement materials exhibiting enhanced properties compared to their binary or ternary equivalents. Here, the authors investigate the influence of microstructure and elemental distribution on the transport and superconducting properties of (TaNb)(1-x)(ZrHfTi)(x) thin films. Superconducting high entropy alloys (HEAs) may combine extraordinary mechanical properties with robust superconductivity. They are suitable model systems for the investigation of the interplay of disorder and superconductivity. Here, we report on the superconductivity in (TaNb)(1-x)(ZrHfTi)(x) thin films. Beyond the near-equimolar region, the films comprise hundreds-of-nanometer-sized crystalline grains and show robust bulk superconductivity. However, the superconducting transitions in these nanocomposites are dramatically suppressed in the near-equimolar configurations, i.e., 0.45 < x < 0.64, where elemental distributions are equivalently homogeneous. Crystal/glass high entropy alloy nanocomposite phase separation was observed for the films in the near-equimolar region, which yields a broadened two-step normal to superconducting transition. Furthermore, the diamagnetic shielding in these films is only observed far below the onset temperature of superconductivity. As these unusual superconducting transitions are observed only in the samples with the high mixing entropy, this compositional range influences the collective electronic properties in these materials.
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| 3. |
- Nocerino, Elisabetta, et al.
(author)
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Competition between magnetic interactions and structural instabilities leading to itinerant frustration in the triangular lattice antiferromagnet LiCrSe2
- 2023
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In: Communications Materials. - : Springer Nature. - 2662-4443. ; 4:1
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Journal article (peer-reviewed)abstract
- LiCrSe2 constitutes a recent valuable addition to the ensemble of two-dimensional triangular lattice antiferromagnets. In this work, we present a comprehensive study of the low temperature nuclear and magnetic structure established in this material. Being subject to a strong magnetoelastic coupling, LiCrSe2 was found to undergo a first order structural transition from a trigonal crystal system (P3 ¯ m1) to a monoclinic one (C2/m) at T s = 30 K. Such restructuring of the lattice is accompanied by a magnetic transition at T N = 30 K. Refinement of the magnetic structure with neutron diffraction data and complementary muon spin rotation analysis reveal the presence of a complex incommensurate magnetic structure with a up-up-down-down arrangement of the chromium moments with ferromagnetic double chains coupled antiferromagnetically. The spin axial vector is also modulated both in direction and modulus, resulting in a spin density wave-like order with periodic suppression of the chromium moment along the chains. This behavior is believed to appear as a result of strong competition between direct exchange antiferromagnetic and superexchange ferromagnetic couplings established between both nearest neighbor and next nearest neighbor Cr3+ ions. We finally conjecture that the resulting magnetic order is stabilized via subtle vacancy/charge order within the lithium layers, potentially causing a mix of two co-existing magnetic phases within the sample.
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| 4. |
- Witteveen, Catherine, et al.
(author)
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Polytypism and superconductivity in the NbS2 system
- 2021
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In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 50:9, s. 3216-3223
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Journal article (peer-reviewed)abstract
- We report on the phase formation and the superconducting properties in the NbS2 system. Specifically, we have performed a series of standardized solid-state syntheses in this system, which allow us to establish a comprehensive synthesis map for the formation of the two polytypes 2H-NbS2 and 3R-NbS2, respectively. We show that the identification of two polytypes by means of X-ray diffraction is not always unambiguous. Our physical property measurements on a phase-pure sample of 3R-NbS2, on a phase-pure sample of 2H-NbS2, and a mixed phase sample confirm earlier reports that 2H-NbS2 is a bulk superconductor and that 3R-NbS2 is not a superconductor above T = 1.75 K. Our results clearly show that specific heat measurements, as true bulk measurements, are crucial for the identification of superconducting materials in this and related systems. Our results indicate that for the investigation of van der Waals materials great care has to be taken on choosing the synthesis conditions for obtaining phase pure samples.
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