“Electron wave-function spillover in self-assembled InAs/InP quantum wires”. Maes J, Hayne M, Sidor Y, Partoens B, Peeters FM, González Y, González L, Fuster D, Garcia JM, Moshchalkov VV, Physical review : B : condensed matter and materials physics 70, 155311 (2004). http://doi.org/10.1103/PhysRevB.70.155311
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 43
DOI: 10.1103/PhysRevB.70.155311
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“Enhancement and decrease of critical current due to suppression of superconductivity by a magnetic field”. Vodolazov DY, Golubovic DS, Peeters FM, Moshchalkov VV, Physical review : B : condensed matter and materials physics 76, 134505 (2007). http://doi.org/10.1103/PhysRevB.76.134505
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 13
DOI: 10.1103/PhysRevB.76.134505
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“Exciton confinement in InAs/InP quantum wires and quantum wells in the presence of a magnetic field”. Sidor Y, Partoens B, Peeters FM, Maes J, Hayne M, Fuster D, González Y, González L, Moshchalkov VV, Physical review : B : condensed matter and materials physics 76, 195320 (2007). http://doi.org/10.1103/PhysRevB.76.195320
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 21
DOI: 10.1103/PhysRevB.76.195320
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“High-field magnetoexcitons in unstrained GaAs/AlxGa1-xAs quantum dots”. Sidor Y, Partoens B, Peeters FM, Schildermans N, Hayne M, Moshchalkov VV, Rastelli A, Schmidt OG, Physical review : B : condensed matter and materials physics 73, 155334 (2006). http://doi.org/10.1103/PhysRevB.73.155334
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 50
DOI: 10.1103/PhysRevB.73.155334
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“Influence of magnet size on magnetically engineered field-induced superconductivity”. Gillijns W, Milošević, MV, Silhanek AV, Moshchalkov VV, Peeters FM, Physical review : B : condensed matter and materials physics 76, 184516 (2007). http://doi.org/10.1103/PhysRevB.76.184516
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 21
DOI: 10.1103/PhysRevB.76.184516
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“Magnetically induced splitting of a giant vortex state in a mesoscopic superconducting disk”. Golubović, DS, Milošević, MV, Peeters FM, Moshchalkov VV, Physical review : B : condensed matter and materials physics 71, 180502 (2005). http://doi.org/10.1103/PhysRevB.71.180502
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 42
DOI: 10.1103/PhysRevB.71.180502
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“Magnetoresistance oscillations in superconducting strips : a Ginzburg-Landau study”. Berdiyorov GR, Chao XH, Peeters FM, Wang HB, Moshchalkov VV, Zhu BY, Physical review : B : condensed matter and materials physics 86, 224504 (2012). http://doi.org/10.1103/PhysRevB.86.224504
Abstract: Within the time-dependent Ginzburg-Landau theory we study the dynamic properties of current-carrying superconducting strips in the presence of a perpendicular magnetic field. We found pronounced voltage peaks as a function of the magnetic field, the amplitude of which depends both on sample dimensions and external parameters. These voltage oscillations are a consequence of moving vortices, which undergo alternating static and dynamic phases. At higher fields or for high currents, the continuous motion of vortices is responsible for the monotonic background on which the resistance oscillations due to the entry of additional vortices are superimposed. Mechanisms for such vortex-assisted resistance oscillations are discussed. Qualitative changes in the magnetoresistance curves are observed in the presence of random defects, which affect the dynamics of vortices in the system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 31
DOI: 10.1103/PhysRevB.86.224504
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“Masking effect of heat dissipation on the current-voltage characteristics of a mesoscopic superconducting sample with leads”. Vodolazov DY, Peeters FM, Morelle M, Moshchalkov VV, Physical review : B : condensed matter and materials physics 71, 184502 (2005). http://doi.org/10.1103/PhysRevB.71.184502
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 43
DOI: 10.1103/PhysRevB.71.184502
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“Optimization of superconducting critical parameters by tuning the size and magnetization of arrays of magnetic dots”. Silhanek AV, Gillijns W, Milošević, MV, Volodin A, Moshchalkov VV, Peeters F, Physical review : B : condensed matter and materials physics 76, 100502 (2007). http://doi.org/10.1103/PhysRevB.76.100502
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 27
DOI: 10.1103/PhysRevB.76.100502
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“Photoluminescence of negatively charged excitons in high magnetic fields”. Hayne M, Jones CL, Bogaerts R, Riva C, Usher A, Peeters FM, Herlach F, Moshchalkov VV, Henini M, Physical review : B : condensed matter and materials physics 59, 2927 (1999). http://doi.org/10.1103/PhysRevB.59.2927
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 86
DOI: 10.1103/PhysRevB.59.2927
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“Superconducting mesoscopic square loop”. Fomin VM, Misko VR, Devreese JT, Moshchalkov VV, Physical Review B 58, 11703 (1998). http://doi.org/10.1103/PhysRevB.58.11703
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 3.836
Times cited: 43
DOI: 10.1103/PhysRevB.58.11703
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“Ultralow blocking temperature and breakdown of the giant spin model in Er3+-doped nanoparticles”. van den Heuvel W, Tikhomirov VK, Kirilenko D, Schildermans N, Chibotaru LF, Vanacken J, Gredin P, Mortier M, Van Tendeloo G, Moshchalkov VV, Physical review : B : condensed matter and materials physics 82, 094421 (2010). http://doi.org/10.1103/PhysRevB.82.094421
Abstract: The magnetization of luminescent Er3+-doped PbF2 nanoparticles (formula Er0.3Pb0.7F2.3) has been studied. Despite the high concentration of the doping Er3+ ions and relatively large size (8 nm) of these nanoparticles we have found no deviation between field-cooled and zero-field-cooled magnetization curves down to T=0.35 K, which points out an ultralow blocking temperature for the reversal of magnetization. We also have found strongly deviating magnetization curves M(H/T) for different temperatures T. These results altogether show that the investigated nanoparticles are not superparamagnetic, but rather each Er3+ ion in these nanoparticles is found in a paramagnetic state down to very low temperatures, which implies the breakdown of the Néel-Brown giant spin model in the case of these nanoparticles. Calculations of magnetization within a paramagnetic model of noninteracting Er3+ ions completely support this conclusion. Due to the ultralow blocking temperature, these nanoparticles have a potential for magnetic field-induced nanoscale refrigeration with an option of their optical localization and temperature control.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 11
DOI: 10.1103/PhysRevB.82.094421
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“Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films”. Adami O-A, Jelić, ŽL, Xue C, Abdel-Hafiez M, Hackens B, Moshchalkov VV, Milošević, MV, Van de Vondel J, Silhanek AV, Physical review: B: condensed matter and materials physics 92, 134506 (2015). http://doi.org/10.1103/PhysRevB.92.134506
Abstract: In 1976, Larkin and Ovchinnikov [Zh. Eksp. Teor. Fiz. 68, 1915 (1975) [Sov. Phys.–JETP 41, 960 (1976)]] predicted that vortex matter in superconductors driven by an electrical current can undergo an abrupt dynamic transition from a flux-flow regime to a more dissipative state at sufficiently high vortex velocities. Typically, this transition manifests itself as a large voltage jump at a particular current density, so-called instability current density J∗, which is smaller than the depairing current. By tuning the effective pinning strength in Al films, using an artificial periodic pinning array of triangular holes, we show that a unique and well-defined instability current density exists if the pinning is strong, whereas a series of multiple voltage transitions appear in the relatively weaker pinning regime. This behavior is consistent with time-dependent Ginzburg-Landau simulations, where the multiple-step transition can be unambiguously attributed to the progressive development of vortex chains and subsequently phase-slip lines. In addition, we explore experimentally the magnetic braking effects, caused by a thick Cu layer deposited on top of the superconductor, on the instabilities and the vortex ratchet effect.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 21
DOI: 10.1103/PhysRevB.92.134506
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“Nonlinear optical properties of Ag nanoclusters and nanoparticles dispersed in a glass host”. Mai HH, Kaydashev VE, Tikhomirov VK, Janssens E, Shestakov MV, Meledina M, Turner S, Van Tendeloo G, Moshchalkov VV, Lievens P, The journal of physical chemistry: C : nanomaterials and interfaces 118, 15995 (2014). http://doi.org/10.1021/jp502294u
Abstract: The nonlinear absorption of Ag atomic clusters and nanoparticles dispersed in a transparent oxyfluoride glass host has been studied. The as-prepared glass, containing 0.15 atom % Ag, shows an absorption band in the UV/violet attributed to the presence of amorphous Ag atomic nanoclusters with an average size of 1.2 nm. Upon heat treatment the Ag nanoclusters coalesce into larger nanoparticles that show a surface plasmon absorption band in the visible. Open aperture z-scan experiments using 480 nm nanosecond laser pulses demonstrated nonsaturated and saturated nonlinear absorption with large nonlinear absorption indices for the Ag nanoclusters and nanoparticles, respectively. These properties are promising, e.g., for applications in optical limiting and objects contrast enhancement.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 43
DOI: 10.1021/jp502294u
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“Optimizing Er/Yb ratio and content in Er-Yb co-doped glass-ceramics for enhancement of the up- and down-conversion luminescence”. Tikhomirov VK, Rodríguez VD, Méndez-Ramos J, del- Castillo J, Kirilenko D, Van Tendeloo G, Moshchalkov VV, Solar energy materials and solar cells 100, 209 (2012). http://doi.org/10.1016/j.solmat.2012.01.019
Abstract: Er3+Yb3+ co-doped transparent glass-ceramics with varying Er/Yb content and ratio have been prepared. High quantum yields for up- and down-conversion luminescence by energy transfer from Yb3+ to Er3+ and from Er3+ to Yb3+, respectively, have been detected and optimized with respect to the Er/Yb content and ratio, and proposed in particular for up- and down-conversion of solar spectrum for enhancement of the efficiency of solar cells. The rise and decay kinetics for the population of the excited levels of Er3+ and Yb3+ have been studied and fit. Based on these experimental data, the mechanisms for the energy transfers have been suggested with emphasis on the optimized Er/Yb content and ratio for enhancement of the efficiency of the Er3+↔Yb3+ energy transfers.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.784
Times cited: 66
DOI: 10.1016/j.solmat.2012.01.019
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“In situ tailoring of superconducting junctions via electro-annealing”. Lombardo J, Jelić, ŽL, Baumans XDA, Scheerder JE, Nacenta JP, Moshchalkov VV, Van de Vondel J, Kramer RBG, Milošević, MV, Silhanek AV, Nanoscale 10, 1987 (2018). http://doi.org/10.1039/C7NR08571K
Abstract: We demonstrate the in situ engineering of superconducting nanocircuitry by targeted modulation of material properties through high applied current densities. We show that the sequential repetition of such customized electro-annealing in a niobium (Nb) nanoconstriction can broadly tune the superconducting critical temperature T-c and the normal-state resistance R-n in the targeted area. Once a sizable R-n is reached, clear magneto-resistance oscillations are detected along with a Fraunhofer-like field dependence of the critical current, indicating the formation of a weak link but with further adjustable characteristics. Advanced Ginzburg-Landau simulations fully corroborate this picture, employing the detailed parametrization from the electrical characterization and high resolution electron microscope images of the region within the constriction where the material has undergone amorphization by electro-annealing.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 7.367
Times cited: 23
DOI: 10.1039/C7NR08571K
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“Formation of stripelike flux patterns obtained by freezing kinematic vortices in a superconducting Pb film”. Silhanek AV, Milošević, MV, Kramer RBG, Berdiyorov GR, Vondel van de J, Luccas RF, Puig T, Peeters FM, Moshchalkov VV, Physical review letters 104 (2010). http://doi.org/10.1103/PhysRevLett.104.017001
Abstract: We demonstrate experimentally and theoretically that the dissipative state of superconducting samples with a periodic array of holes at high current densities consists of flux rivers resulting from a short-range attractive interaction between vortices. This dynamically induced vortex-vortex attraction results from the migration of quasiparticles out of the vortex core (kinematic vortices). We have directly visualized the formation of vortex chains by scanning Hall probe microscopy after freezing the dynamic state by a field cooling procedure at a constant bias current. Similar experiments carried out in a sample without holes show no hint of flux river formation. We shed light on this nonequilibrium phenomena modeled by time-dependent Ginzburg-Landau simulations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 60
DOI: 10.1103/PhysRevLett.104.017001
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“Stable vortex-antivortex molecules in mesoscopic superconducting triangles”. Misko VR, Fomin VM, Devreese JT, Moshchalkov VV, Physical Review Letters 90, 147003 (2003). http://doi.org/10.1103/PhysRevLett.90.147003
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 8.462
Times cited: 103
DOI: 10.1103/PhysRevLett.90.147003
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“Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors”. Li J, Ji M, Schwarz T, Ke X, Van Tendeloo G, Yuan J, Pereira PJ, Huang Y, Zhang G, Feng HL, Yuan YH, Hatano T, Kleiner R, Koelle D, Chibotaru LF, Yamaura K, Wang HB, Wu PH, Takayama-Muromachi E, Vanacken J, Moshchalkov VV;, Nature communications 6, 7614 (2015). http://doi.org/10.1038/ncomms8614
Abstract: The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm2 cross-section. The impurities suppress superconductivity in a three-dimensional Swiss cheese-like pattern with in-plane and out-of-plane characteristic lengths slightly below ~1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 12
DOI: 10.1038/ncomms8614
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“Nematic superconducting state in iron pnictide superconductors”. Li J, Pereira PJ, Yuan J, Lv Y-Y, Jiang M-P, Lu D, Lin Z-Q, Liu Y-J, Wang J-F, Li L, Ke X, Van Tendeloo G, Li M-Y, Feng H-L, Hatano T, Wang H-B, Wu P-H, Yamaura K, Takayama-Muromachi E, Vanacken J, Chibotaru LF, Moshchalkov VV, Nature communications 8, 1880 (2017). http://doi.org/10.1038/s41467-017-02016-y
Abstract: Nematic order often breaks the tetragonal symmetry of iron-based superconductors. It arises from regular structural transition or electronic instability in the normal phase. Here, we report the observation of a nematic superconducting state, by measuring the angular dependence of the in-plane and out-of-plane magnetoresistivity of Ba 0.5 K 0.5 Fe 2 As 2 single crystals. We find large twofold oscillations in the vicinity of the superconducting transition, when the direction of applied magnetic field is rotated within the basal plane. To avoid the influences from sample geometry or current flow direction, the sample was designed as Corbino-shape for in-plane and mesa-shape for out-of-plane measurements. Theoretical analysis shows that the nematic superconductivity arises from the weak mixture of the quasi-degenerate s-wave and d-wave components of the superconducting condensate, most probably induced by a weak anisotropy of stresses inherent to single crystals.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 8
DOI: 10.1038/s41467-017-02016-y
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“Capturing wetting states in nanopatterned silicon”. Xu X, Vereecke G, Chen C, Pourtois G, Armini S, Verellen N, Tsai WK, Kim DW, Lee E, Lin CY, Van Dorpe P, Struyf H, Holsteyns F, Moshchalkov V, Indekeu J, De Gendt S;, ACS nano 8, 885 (2014). http://doi.org/10.1021/nn405621w
Abstract: Spectacular progress in developing advanced Si circuits with reduced size, along the track of Moore's law, has been relying on necessary developments in wet cleaning of nanopatterned Si wafers to provide contaminant free surfaces. The most efficient cleaning is achieved when complete wetting can be realized. In this work, ordered arrays of silicon nanopillars on a hitherto unexplored small scale have been used to study the wetting behavior on nanomodulated surfaces in a substantial range of surface treatments and geometrical parameters. With the use of optical reflectance measurements, the nanoscale water imbibition depths have been measured and the transition to the superhydrophobic Cassie-Baxter state has been accurately determined. For pillars of high aspect ratio (about 15), the transition occurs even when the surface is grafted with a hydrophilic functional group. We have found a striking consistent deviation between the contact angle measurements and the straightforward application of the classical wetting models. Molecular dynamics simulations show that these deviations can be attributed to the long overlooked atomic-scale surface perturbations that are introduced during the nanofabrication process. When the transition condition is approached, transient states of partial imbibition that characterize intermediate states between the Wenzel and Cassie-Baxter states are revealed in our experiments.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 13.942
Times cited: 39
DOI: 10.1021/nn405621w
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“Global and local superconductivity in boron-doped granular diamond”. Zhang G, Turner S, Ekimov EA, Vanacken J, Timmermans M, Samuely T, Sidorov VA, Stishov SM, Lu Y, Deloof B, Goderis B, Van Tendeloo G, Van de Vondel J, Moshchalkov VV;, Advanced materials 26, 2034 (2014). http://doi.org/10.1002/adma.201304667
Abstract: Strong granularity-correlated and intragrain modulations of the superconducting order parameter are demonstrated in heavily boron-doped diamond situated not yet in the vicinity of the metal-insulator transition. These modulations at the superconducting state (SC) and at the global normal state (NS) above the resistive superconducting transition, reveal that local Cooper pairing sets in prior to the global phase coherence.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 34
DOI: 10.1002/adma.201304667
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“Classification and control of the origin of photoluminescence from Si nanocrystals”. Godefroo S, Hayne M, Jivanescu M, Stesmans A, Zacharias M, Lebedev OI, Van Tendeloo G, Moshchalkov VV, Nature nanotechnology 3, 174 (2008). http://doi.org/10.1038/nnano.2008.7
Abstract: Silicon dominates the electronics industry, but its poor optical properties mean that III-V compound semiconductors are preferred for photonics applications. Photoluminescence at visible wavelengths was observed from porous Si at room temperature in 1990, but the origin of these photons (do they arise from highly localized defect states or quantum confinement effects?) has been the subject of intense debate ever since. Attention has subsequently shifted from porous Si to Si nanocrystals, but the same fundamental question about the origin of the photoluminescence has remained. Here we show, based on measurements in high magnetic fields, that defects are the dominant source of light from Si nanocrystals. Moreover, we show that it is possible to control the origin of the photoluminescence in a single sample: passivation with hydrogen removes the defects, resulting in photoluminescence from quantum-confined states, but subsequent ultraviolet illumination reintroduces the defects, making them the origin of the light again.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 38.986
Times cited: 426
DOI: 10.1038/nnano.2008.7
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