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“Electron-hole symmetry and solutions of Richardson pairing model”. Pogosov WV, Lin N, Misko VR, European physical journal : B : condensed matter and complex systems 86, 235 (2013). http://doi.org/10.1140/epjb/e2013-40234-9
Abstract: Richardson approach provides an exact solution of the pairing Hamiltonian. This Hamiltonian is characterized by the electron-hole pairing symmetry, which is however hidden in Richardson equations. By analyzing this symmetry and using an additional conjecture, fulfilled in solvable limits, we suggest a simple expression of the ground state energy for an equally-spaced energy-level model, which is applicable along the whole crossover from the superconducting state to the pairing fluctuation regime. Solving Richardson equations numerically, we demonstrate a good accuracy of our expression.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 6
DOI: 10.1140/epjb/e2013-40234-9
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“Density dependence of the rectification of vortex motion in a circular asymmetric channel”. Lin NS, Misko VR, Heitmann TW, Yu K, Plourde BLT, Physica: C : superconductivity 479, 137 (2012). http://doi.org/10.1016/j.physc.2011.12.028
Abstract: We study the rectification of vortex motion in an asymmetric ring channel in a Corbino setup. With an applied ac current, the motion of vortices in the channel is rectified by the asymmetric potential and induces a dc net flow. The net flow in such a system strongly depends on vortex density, and we distinguish “single-vortex'' rectification regime (for low density, when each vortex is rectified individually) determined by the potential-energy landscape inside each cell of the channel and ”multi-vortex'', or "collective'', rectification (high density case) when the interaction between vortices becomes important. (C) 2012 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.404
DOI: 10.1016/j.physc.2011.12.028
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“Rectification of vortex motion in a circular ratchet channel”. Lin NS, Heitmann TW, Yu K, Plourde BLT, Misko VR, Physical review : B : condensed matter and materials physics 84, 144511 (2011). http://doi.org/10.1103/PhysRevB.84.144511
Abstract: We study the dynamics of vortices in an asymmetric (i.e., consisting of triangular cells) ring channel driven by an external ac current I in a Corbino setup. The asymmetric potential rectifies the motion of vortices and induces a net vortex flow without any unbiased external drive, i.e., the ratchet effect. We show that the net flow of vortices strongly depends on vortex density and frequency of the driving current. Depending on the density, we distinguish a single-vortex rectification regime (for low density, when each vortex is rectified individually) determined by the potential-energy landscape inside each cell of the channel (i.e., hard and easy directions) and multi-vortex, or collective, rectification (high-density case) when the inter-vortex interaction becomes important. We analyze the average angular velocity ω of vortices as a function of I and study commensurability effects between the numbers of vortices and cells in the channel and the role of frequency of the applied ac current. We have shown that the commensurability effect results in a stepwise ω-I curve. Besides the integer steps, i.e., the large steps found in the single-vortex case, we also found fractional steps corresponding to fractional ratios between the numbers of vortices and triangular cells. We have performed preliminary measurements on a device containing a single weak-pinning circular ratchet channel in a Corbino geometry and observed a substantial asymmetric vortex response.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 27
DOI: 10.1103/PhysRevB.84.144511
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“Dynamics of multishell vortex structures in mesoscopic superconducting Corbino disks”. Lin NS, Misko VR, Peeters FM, Physical review : B : condensed matter and materials physics 81, 134504 (2010). http://doi.org/10.1103/PhysRevB.81.134504
Abstract: We study the dynamics of vortex shells in mesoscopic superconducting Corbino disks, where vortices form shells as recently observed in micrometer-sized Nb disks. Due to the interplay between the vortex-vortex interaction, the gradient Lorentz force and the (in)commensurability between the numbers of vortices in shells, the process of angular melting of vortex-shell configurations becomes complex. Angular melting can start either from the center of the disk (where the shear stress is maximum) or from its boundary (where the shear stress is minimum) depending on the specific vortex configuration. Furthermore, we found that two kinds of defects can exist in such vortex-shell structures: intrashell and intershell defects. An intrashell defect may lead to an inverse dynamic behavior, i.e., one of the vortex shells under a stronger driving force can rotate slower than the adjacent shell that is driven by a weaker Lorentz force. An intershell defect always locks more than two shells until the gradient of the Lorentz force becomes large enough to break the rigid-body rotation of the locked shells. Such a lock-unlock process leads to hysteresis in the angular velocities of the shells.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 11
DOI: 10.1103/PhysRevB.81.134504
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“Unconventional dynamics of vortex shells in mesoscopic superconducting corbino disks”. Misko VR, Lin NS, Peeters FM, Physica: C : superconductivity 470, 939 (2010). http://doi.org/10.1016/j.physc.2010.02.058
Abstract: The dynamics of vortex matter in mesoscopic superconducting Corbino disk is strongly influenced by the discrete vortex structure arranged in shells. While in previous works the vortex dynamics has been studied in large (macroscopic) and in very small mesoscopic disks (containing only few shells), in the intermediate-size regime it is much more complex and unusual, due to: (i) the competition between the vortexvortex interaction and confinement and (ii) (in)commensurability among the vortex shells. We found that the interplay between these effects can result in a very unusual vortex dynamical behavior: (i) unconventional angular melting (i.e., propagating from the boundary, where the shear stress is minimum, towards the center) and (ii) unconventional dynamics of shells (i.e., the inversion of shell velocities with respect to the gradient driving force). This unusual behavior is found for different number of shells.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.404
Times cited: 3
DOI: 10.1016/j.physc.2010.02.058
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“Unconventional vortex dynamics in mesoscopic superconducting corbino disks”. Lin NS, Misko VR, Peeters FM, Physical review letters 102, 197003 (2009). http://doi.org/10.1103/PhysRevLett.102.197003
Abstract: The discrete shell structure of vortex matter strongly influences the flux dynamics in mesoscopic superconducting Corbino disks. While the dynamical behavior is well understood in large and in very small disks, in the intermediate-size regime it occurs to be much more complex and unusual, due to (in)commensurability between the vortex shells. We demonstrate unconventional vortex dynamics (inversion of shell velocities with respect to the gradient driving force) and angular melting (propagating from the boundary where the shear stress is minimum, towards the center) in mesoscopic Corbino disks.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 18
DOI: 10.1103/PhysRevLett.102.197003
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“KNd(MoO4)2: a new incommensurate modulated structure in the scheelite family”. Morozov VA, Arakcheeva AV, Chapuis G, Guiblin N, Rossell MD, Van Tendeloo G, Chemistry of materials 18, 4075 (2006). http://doi.org/10.1021/cm0605668
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 46
DOI: 10.1021/cm0605668
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Lin N (2012) Dynamics of interacting clusters in low-dimensional superconductors. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Deeper insights into the photoluminescence properties and (photo)chemical reactivity of cadmium red (CdS1-xSex) paints in renowned twentieth century paintings by state-of-the-art investigations at multiple length scales”. Monico L, Rosi F, Vivani R, Cartechini L, Janssens K, Gauquelin N, Chezganov D, Verbeeck J, Cotte M, D'Acapito F, Barni L, Grazia C, Buemi LP, Andral J-L, Miliani C, Romani A, The European Physical Journal Plus 137, 311 (2022). http://doi.org/10.1140/EPJP/S13360-022-02447-7
Abstract: Cadmium red is the name used for denoting a class of twentieth century artists' pigments described by the general formula CdS1-xSex. For their vibrant hues and excellent covering power, a number of renowned modern and contemporary painters, including Jackson Pollock, often used cadmium reds. As direct band gap semiconductors, CdS1-xSex compounds undergo direct radiative recombination (with emissions from the green to orange region) and radiative deactivation from intragap trapping states due to crystal defects, which give rise to two peculiar red-NIR emissions, known as deep level emissions (DLEs). The positions of the DLEs mainly depend on the Se content of CdS1-xSex; thus, photoluminescence and diffuse reflectance vis-NIR spectroscopy have been profitably used for the non-invasive identification of different cadmium red varieties in artworks over the last decade. Systematic knowledge is however currently lacking on what are the parameters related to intrinsic crystal defects of CdS1-xSex and environmental factors influencing the spectral properties of DLEs as well as on the overall (photo)chemical reactivity of cadmium reds in paint matrixes. Here, we present the application of a novel multi-length scale and multi-method approach to deepen insights into the photoluminescence properties and (photo)chemical reactivity of cadmium reds in oil paintings by combining both well established and new non-invasive/non-destructive analytical techniques, including macro-scale vis-NIR and vibrational spectroscopies and micro-/nano-scale advanced electron microscopy mapping and X-ray methods employing synchrotron radiation and conventional sources. Macro-scale vis-NIR spectroscopy data obtained from the in situ non-invasive analysis of nine masterpieces by Gerardo Dottori, Jackson Pollock and Nicolas de Stael allowed classifying the CdS1-xSex-paints in three groups, according to the relative intensity of the two DLE bands. These outcomes, combined with results from micro-/nano-scale electron microscopy mapping and X-ray analysis of a set of CdS1-xSex powders and artificially aged paint mock-ups, indicated that the relative intensity of DLEs is not affected by the morphology, microstructure and local atomic environment of the pigment particles but it is influenced by the presence of moisture. Furthermore, the extensive study of artificially aged oil paint mock-ups permitted us to provide first evidence of the tendency of cadmium reds toward photo-degradation and to establish that the conversion of CdS1-xSex to CdSO4 and/or oxalates is triggered by the oil binding medium and moisture level and depends on the Se content. Based on these findings, we could interpret the localized presence of CdSO4 and cadmium oxalate as alteration products of the original cadmium red paints in two paintings by Pollock.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 3.4
Times cited: 3
DOI: 10.1140/EPJP/S13360-022-02447-7
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“The role of SnF₂, additive on interface formation in all lead-free FASnI₃, perovskite solar cells”. Zillner J, Boyen H-G, Schulz P, Hanisch J, Gauquelin N, Verbeeck J, Kueffner J, Desta D, Eisele L, Ahlswede E, Powalla M, Advanced functional materials , 2109649 (2022). http://doi.org/10.1002/ADFM.202109649
Abstract: Tin-based perovskites are promising alternative absorber materials for leadfree perovskite solar cells but need strategies to avoid fast tin (Sn) oxidation. Generally, this reaction can be slowed down by the addition of tin fluoride (SnF2) to the perovskite precursor solution, which also improves the perovskite layer morphology. Here, this work analyzes the spatial distribution of the additive within formamidinium tin triiodide (FASnI(3)) films deposited on top of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transporting layers. Employing time-of-flight secondary ion mass spectrometry and a combination of hard and soft X-ray photoelectron spectroscopy, it is found that Sn F2 preferably accumulates at the PEDOT:PSS/perovskite interface, accompanied by the formation of an ultrathin SnS interlayer with an effective thickness of approximate to 1.2 nm.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19
Times cited: 22
DOI: 10.1002/ADFM.202109649
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“Engineering properties by long range symmetry propagation initiated at perovskite heterostructure interface”. Liao ZL, Green RJ, Gauquelin N, Gonnissen J, Van Aert S, Verbeeck J, et al, Advanced functional materials , 1 (2016)
Abstract: In epitaxial thin film systems, the crystal structure and its symmetry deviate from the bulk counterpart due to various mechanisms such as epitaxial strain and interfacial structural coupling, which induce an accompanying change in their properties. In perovskite materials, the crystal symmetry can be described by rotations of 6-fold coordinated transition metal oxygen octahedra, which are found to be altered at interfaces. Here, we unravel how the local oxygen octahedral coupling (OOC) at perovskite heterostructural interfaces initiates a different symmetry in epitaxial films and provide design rules to induce various symmetries in thin films by careful selecting appropriate combinations of substrate/buffer/film. Very interestingly we discovered that these combinations lead to symmetry changes throughout the full thickness of the film. Our results provide a deep insight into understanding the origin of induced crystal symmetry in a perovskite heterostructure and an intelligent route to achieve unique functional properties.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
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