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“Tunable Snell's law for spin waves in heterochiral magnetic films”. Mulkers J, Van Waeyenberge B, Milošević, MV, Physical review B 97, 104422 (2018). http://doi.org/10.1103/PhysRevB.97.104422
Abstract: Thin ferromagnetic films with an interfacially induced DMI exhibit nontrivial asymmetric dispersion relations that lead to unique and useful magnonic properties. Here we derive an analytical expression for the magnon propagation angle within the micromagnetic framework and show how the dispersion relation can be approximated with a comprehensible geometrical interpretation in the k space of the propagation of spin waves. We further explore the refraction of spin waves at DMI interfaces in heterochiral magnetic films, after deriving a generalized Snell's law tunable by an in-plane magnetic field, that yields analytical expressions for critical incident angles. The found asymmetric Brewster angles at interfaces of regions with different DMI strengths, adjustable by magnetic field, support the conclusion that heterochiral ferromagnetic structures are an ideal platform for versatile spin-wave guides.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 20
DOI: 10.1103/PhysRevB.97.104422
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“Electrostatics of electron-hole interactions in van der Waals heterostructures”. Cavalcante LSR, Chaves A, Van Duppen B, Peeters FM, Reichman DR, Physical review B 97, 125427 (2018). http://doi.org/10.1103/PhysRevB.97.125427
Abstract: The role of dielectric screening of electron-hole interaction in van der Waals heterostructures is theoretically investigated. A comparison between models available in the literature for describing these interactions is made and the limitations of these approaches are discussed. A simple numerical solution of Poisson's equation for a stack of dielectric slabs based on a transfer matrix method is developed, enabling the calculation of the electron-hole interaction potential at very low computational cost and with reasonable accuracy. Using different potential models, direct and indirect exciton binding energies in these systems are calculated within Wannier-Mott theory, and a comparison of theoretical results with recent experiments on excitons in two-dimensional materials is discussed.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 22
DOI: 10.1103/PhysRevB.97.125427
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“Quantitative modeling of secondary electron emission from slow-ion bombardment on semiconductors”. Bercx M, Partoens B, Lamoen D, Physical review B 99, 085413 (2019). http://doi.org/10.1103/PhysRevB.99.085413
Abstract: When slow ions incident on a surface are neutralized, the excess potential energy is passed on to an electron inside the surface, leading to emission of secondary electrons. The microscopic description of this process, as
well as the calculation of the secondary electron yield, is a challenging problem due to its complexity as well
as its sensitivity to surface properties. One of the first quantitative descriptions was articulated in the 1950s by
Hagstrum, who based his calculation on a parametrization of the density of states of the material. In this paper, we
present a model for calculating the secondary electron yield, derived from Hagstrum’s initial approach. We use
first-principles density functional theory calculations to acquire the necessary input and introduce the concept of
electron cascades to Hagstrum’s model in order to improve the calculated spectra, as well as remove its reliance
on fitting parameters. We apply our model to He+ and Ne+ ions incident on Ge(111) and Si(111) and obtain
yield spectra that match closely to the experimental results of Hagstrum.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 5
DOI: 10.1103/PhysRevB.99.085413
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“Single femtosecond laser pulse excitation of individual cobalt nanoparticles”. Savchenko TM, Buzzi M, Howald L, Ruta S, Vijayakumar J, Timm M, Bracher D, Saha S, Derlet PM, Béché, A, Verbeeck J, Chantrell RW, Vaz CAF, Nolting F, Kleibert A, Physical Review B 102, 205418 (2020). http://doi.org/10.1103/PhysRevB.102.205418
Abstract: Laser-induced manipulation of magnetism at the nanoscale is a rapidly growing research topic with potential for applications in spintronics. In this work, we address the role of the scattering cross section, thermal effects, and laser fluence on the magnetic, structural, and chemical stability of individual magnetic nanoparticles excited by single femtosecond laser pulses. We find that the energy transfer from the fs laser pulse to the nanoparticles is limited by the Rayleigh scattering cross section, which in combination with the light absorption of the supporting substrate and protective layers determines the increase in the nanoparticle temperature. We investigate individual Co nanoparticles (8 to 20 nm in size) as a prototypical model system, using x-ray photoemission electron microscopy and scanning electron microscopy upon excitation with single femtosecond laser pulses of varying intensity and polarization. In agreement with calculations, we find no deterministic or stochastic reversal of the magnetization in the nanoparticles up to intensities where ultrafast demagnetization or all-optical switching is typically reported in thin films. Instead, at higher fluences, the laser pulse excitation leads to photo-chemical reactions of the nanoparticles with the protective layer, which results in an irreversible change in the magnetic properties. Based on our findings, we discuss the conditions required for achieving laser-induced switching in isolated nanomagnets.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.7
Times cited: 1
DOI: 10.1103/PhysRevB.102.205418
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“Distinctive magnetic properties of CrI3 and CrBr3 monolayers caused by spin-orbit coupling”. Bacaksiz C, Šabani D, Menezes RM, Milošević, MV, Physical Review B 103, 125418 (2021). http://doi.org/10.1103/PhysRevB.103.125418
Abstract: After the discovery of magnetism in monolayer CrI3, the magnetic properties of different 2D materials from the chromium-trihalide family are intuitively assumed to be similar, yielding magnetic anisotropy from the spin-orbit coupling on halide ligands. Here we reveal significant differences between the CrI3 and CrBr3 magnetic monolayers in their magnetic anisotropy, resulting Curie temperature, hysteresis in external magnetic field, and evolution of magnetism with strain, all predominantly attributed to distinctly different interplay of atomic contributions to spin-orbit coupling in two materials.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 18
DOI: 10.1103/PhysRevB.103.125418
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“Finite-temperature vortices in a rotating Fermi gas”. Klimin SN, Tempere J, Verhelst N, Milošević, MV, Physical review A 94, 023620 (2016). http://doi.org/10.1103/PhysRevA.94.023620
Abstract: Vortices and vortex arrays have been used as a hallmark of superfluidity in rotated, ultracold Fermi gases. These superfluids can be described in terms of an effective field theory for a macroscopic wave function representing the field of condensed pairs, analogous to the Ginzburg-Landau theory for superconductors. Here we establish how rotation modifies this effective field theory, by rederiving it starting from the action of Fermi gas in the rotating frame of reference. The rotation leads to the appearance of an effective vector potential, and the coupling strength of this vector potential to the macroscopic wave function depends on the interaction strength between the fermions, due to a renormalization of the pair effective mass in the effective field theory. The mass renormalization derived here is in agreement with results of functional renormalization-group theory. In the extreme Bose-Einstein condensate regime, the pair effective mass tends to twice the fermion mass, in agreement with the physical picture of a weakly interacting Bose gas of molecular pairs. Then we use our macroscopic-wave-function description to study vortices and the critical rotation frequencies to form them. Equilibrium vortex state diagrams are derived and they are in good agreement with available results of the Bogoliubov-de Gennes theory and with experimental data.
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Impact Factor: 2.925
Times cited: 6
DOI: 10.1103/PhysRevA.94.023620
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“Skyrmionic vortex lattices in coherently coupled three-component Bose-Einstein condensates”. Orlova NV, Kuopanportti P, Milošević, MV, Physical Review A 94, 023617 (2016). http://doi.org/10.1103/PHYSREVA.94.023617
Abstract: We show numerically that a harmonically trapped and coherently Rabi-coupled three-component Bose-Einstein condensate can host unconventional vortex lattices in its rotating ground state. The discovered lattices incorporate square and zig-zag patterns, vortex dimers and chains, and doubly quantized vortices, and they can be quantitatively classified in terms of a skyrmionic topological index, which takes into account the multicomponent nature of the system. The exotic ground-state lattices arise due to the intricate interplay of the repulsive density-density interactions and the Rabi couplings as well as the ubiquitous phase frustration between the components. In the frustrated state, domain walls in the relative phases can persist between some components even at strong Rabi coupling, while vanishing between others. Consequently, in this limit the three-component condensate effectively approaches a two-component condensate with only density-density interactions. At intermediate Rabi coupling strengths, however, we face unique vortex physics that occurs neither in the two-component counterpart nor in the purely density-density-coupled three-component system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.925
Times cited: 16
DOI: 10.1103/PHYSREVA.94.023617
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“Nontarget biomolecules alter macromolecular changes induced by bactericidal low-temperature plasma”. Privat-Maldonado A, Gorbanev Y, O'Connell D, Vann R, Chechik V, van der Woude MW, IEEE transactions on radiation and plasma medical sciences 2, 121 (2018). http://doi.org/10.1109/TRPMS.2017.2761405
Abstract: Low-temperature plasmas (LTPs) have a proven bactericidal activity governed by the generated reactive oxygen and nitrogen species (RONS) that target microbial cell components. However, RONS also interact with biomolecules in the environment. Here we assess the impact of these interactions upon exposure of liquid suspensions with variable organic content to an atmospheric-pressure dielectric barrier discharge plasma jet. Salmonella enterica serovar Typhimurium viability in the suspension was reduced in the absence [e. g., phosphate buffered saline (PBS)], but not in the presence of (high) organic content [Dulbecco's Modified Eagle's Medium (DMEM), DMEM supplemented with foetal calf serum, and Lysogeny Broth]. The reduced viability of LTP-treated bacteria in PBS correlated to a loss of membrane integrity, whereas double-strand DNA breaks could not be detected in treated single cells. The lack of bactericidal activity in solutions with high organic content correlated with a relative decrease of center dot OH and O-3/O-2(a(1)Delta g)/O, and an increase of H2O2 and NO2- in the plasma-treated solutions. These results indicate that the redox reactions of LTP-generated RONS with nontarget biomolecules resulted in a RONS composition with reduced bactericidal activity. Therefore, the chemical composition of the bacterial environment should be considered in the development of LTP for antimicrobial treatment, and may affect other biomedical applications as well.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1109/TRPMS.2017.2761405
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“Low-Temperature Plasma for Biology, Hygiene, and Medicine: Perspective and Roadmap”. Laroussi M, Bekeschus S, Keidar M, Bogaerts A, Fridman A, Lu X, Ostrikov K, Hori M, Stapelmann K, Miller V, Reuter S, Laux C, Mesbah A, Walsh J, Jiang C, Thagard SM, Tanaka H, Liu D, Yan D, Yusupov M, IEEE transactions on radiation and plasma medical sciences 6, 127 (2022). http://doi.org/10.1109/TRPMS.2021.3135118
Abstract: Plasma, the fourth and most pervasive state of matter in the visible universe, is a fascinating medium that is connected to the beginning of our universe itself. Man-made plasmas are at the core of many technological advances that include the fabrication of semiconductor devices, which enabled the modern computer and communication revolutions. The introduction of low temperature, atmospheric pressure plasmas to the biomedical field has ushered a new revolution in the healthcare arena that promises to introduce plasma-based therapies to combat some thorny and long-standing medical challenges. This article presents an overview of where research is at today and discusses innovative concepts and approaches to overcome present challenges and take the field to the next level. It is written by a team of experts who took an in-depth look at the various applications of plasma in hygiene, decontamination, and medicine, made critical analysis, and proposed ideas and concepts that should help the research community focus their efforts on clear and practical steps necessary to keep the field advancing for decades to come.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1109/TRPMS.2021.3135118
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“ZnN and ZnP as novel graphene-like materials with high Li-ion storage capacities”. Mortazavi B, Bafekry A, Shahrokhi M, Rabczuk T, Zhuang X, Materials today energy 16, Unsp 100392 (2020). http://doi.org/10.1016/J.MTENER.2020.100392
Abstract: In this work, we employed first-principles density functional theory (DFT) calculations to investigate the dynamical and thermal stability of graphene-like ZnX (X = N, P, As) nanosheets. We moreover analyzed the electronic, mechanical and optical properties of these novel two-dimensional (2D) systems. Acquired phonon dispersion relations reveal the absence of imaginary frequencies and thus confirming the dynamical stability of predicted monolayers. According to ab-initio molecular dynamics results however only ZnN and ZnP exhibit the required thermally stability. The elastic modulus of ZnN, ZnP and ZnAs are estimated to be 31, 21 and 17 N/m, respectively, and the corresponding tensile strengths values are 6.0, 4.9 and 4.0 N/m, respectively. Electronic band structure analysis confirms the metallic electronic character for the predicted monolayers. Results for the optical characteristics also indicate a reflectivity of 100% at extremely low energy levels, which is desirable for photonic and optoelectronic applications. According to our results, graphene-like ZnN and ZnP nanosheets can yield high capacities of 675 and 556 mAh/g for Li-ion storage, respectively. Acquired results confirm the stability and acceptable strength of ZnN and ZnP nanosheets and highlight their attractive application prospects in optical and energy storage systems.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 9.3
Times cited: 13
DOI: 10.1016/J.MTENER.2020.100392
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“Developing feature-rich electronic and magnetic properties in the beta-As monolayer for spintronic and optoelectronic applications by C and Si doping : a first-principles study”. Hoat DM, Duy Khanh Nguyen, Bafekry A, Vo Van On, Ul Haq B, Hoang D-Q, Cocoletzi GH, Rivas-Silva JF, Surfaces and interfaces 27, 101534 (2021). http://doi.org/10.1016/J.SURFIN.2021.101534
Abstract: In this work, the carbon (C) and silicon (Si) doping and codoping effects on beta-arsenene (As) monolayer structural, electronic, and magnetic properties have been comprehensively investigated using first-principles calculations. The studied two-dimensional (2D) materials exhibit good stability. Pristine beta-As single layer is an indirect gap semiconductor with a band gap of 1.867(2.441) eV as determined by PBE(HSE06) functional. Due to the difference in atomic size and electronic interactions, C and Si substitution induces a significant local structural distortion. Depending upon dopant concentration and doping sites, feature-rich electronic properties including non-magnetic semiconductor, magnetic semiconductor and half-metallicity may be obtained, which result from p-p interactions. High spin-polarization at the Fermi level vicinity and significant magnetism suggest As:1C, As:2C, As:1Si, As:2Si, and As:CSi systems as prospective spintronic 2D materials. While, the C-C, Si-Si, and C-Si dimer doping decreases electronic band gap, making the layer more suitable for applications in optoelectronic devices. Results presented herein may suggest an efficient approach to create novel multi-functional 2D materials from beta-As monolayer.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1016/J.SURFIN.2021.101534
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“Occupancy of lattice positions probed by X-ray photoelectron diffraction : a case study of tetradymite topological insulators”. Vladimirova NV, Frolov AS, Sanchez-Barriga J, Clark OJ, Matsui F, Usachov DY, Muntwiler M, Callaert C, Hadermann J, Neudachina VS, Tamm ME, Yashina LV, Surfaces and interfaces 36, 102516 (2023). http://doi.org/10.1016/J.SURFIN.2022.102516
Abstract: Occupancy of different structural positions in a crystal lattice often seems to play a key role in material prop-erties. Several experimental techniques have been developed to uncover this issue, all of them being mostly bulk sensitive. However, many materials including topological insulators (TIs), which are among the most intriguing modern materials, are intended to be used in devices as thin films, for which the sublattice occupancy may differ from the bulk. One of the possible approaches to occupancy analysis is X-ray Photoelectron Diffraction (XPD), a structural method in surface science with chemical sensitivity. We applied this method in a case study of Sb2(Te1-xSex)3 mixed crystals, which belong to prototypical TIs. We used high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) as a reference method to verify our analysis. We revealed that the XPD data for vacuum cleaved bulk crystals are in excellent agreement with the reference ones. Also, we demonstrate that the anion occupancy near a naturally formed surface can be rather different from that of the bulk. The present results are relevant for a wide range of compositions where the system remains a topological phase, as we ultimately show by probing the transiently occupied topological surface state above the Fermi level by ultrafast photoemission.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.2
DOI: 10.1016/J.SURFIN.2022.102516
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“Ab initio calculations and a scratch test study of RF-magnetron sputter deposited hydroxyapatite and silicon-containing hydroxyapatite coatings”. Surmenev RA, Grubova IY, Neyts E, Teresov AD, Koval NN, Epple M, Tyurin AI, Pichugin VF, Chaikina MV, Surmeneva MA, Surfaces and interfaces 21 (2020). http://doi.org/10.1016/J.SURFIN.2020.100727
Abstract: A crucial property for implants is their biocompatibility. To ensure biocompatibility, thin coatings of hydroxyapatite (HA) are deposited on the actual implant. In this study, we investigate the effects of the addition of silicate anions to the structure of hydroxyapatite coatings on their adhesion strength via a scratch test and ab initio calculations. We find that both the grain size and adhesion strength decrease with the increase in the silicon content in the HA coating (SiHA). The increase in the silicon content to 1.2 % in the HA coating leads to a decrease in the average crystallite size from 28 to 21 nm, and in the case of 4.6 %, it leads to the formation of an amorphous or nanocrystalline film. The decreases in the grain and crystallite sizes lead to peeling and destruction of the coating from the titanium substrate at lower loads. Further, our ab initio simulations demonstrate an increased number of molecular bonds at the amorphous SiHA-TiO2 interface. However, the experimental results revealed that the structure and grain size have more pronounced effects on the adhesion strength of the coatings. In conclusion, based on the results of the ab initio simulations and the experimental results, we suggest that the presence of Si in the form of silicate ions in the HA coating has a significant impact on the structure, grain size, and number of molecular bonds at the interface and on the adhesion strength of the SiHA coating to the titanium substrate.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.2
DOI: 10.1016/J.SURFIN.2020.100727
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“Exploring the adsorption mechanisms of neurotransmitter and amino acid on Ti3C2-MXene monolayer : insights from DFT calculations”. Ozdemir I, Arkin H, Milošević, MV, V Barth J, Aktuerk E, Surfaces and interfaces 46, 104169 (2024). http://doi.org/10.1016/J.SURFIN.2024.104169
Abstract: In this study, we conducted a systematic density functional theory (DFT) investigation of the interaction between Ti3C2-MXene monolayer and biological molecules dopamine (DA) and serine (Ser) as neurotransmitter and amino acid, respectively. Our calculations show good agreement with previous literature findings for the optimized Ti3C2 monolayer. We found that DA and Ser molecules bind to the Ti3C2 surface with adsorption energies of -2.244 eV and -3.960 eV, respectively. The adsorption of Ser resulted in the dissociation of one H atom. Electronic density of states analyses revealed little changes in the electronic properties of the Ti3C2-MXene monolayer upon adsorption of the biomolecules. We further investigated the interaction of DA and Ser with Ti3C2 monolayers featuring surface -termination with OH functional group, and Ti -vacancy. Our calculations indicate that the adsorption energies significantly decrease in the presence of surface termination, with adsorption energies of -0.097 eV and -0.330 eV for DA and Ser, respectively. Adsorption energies on the Ti -vacancy surface, on the other hand, are calculated to be -3.584 eV and -3.856 eV for DA and Ser, respectively. Our results provide insights into the adsorption behavior of biological molecules on Ti3C2-MXene, demonstrating the potential of this material for biosensing and other biomedical applications. These findings highlight the importance of surface modifications in the development of functional materials and devices based on Ti3C2-MXene, and pave the way for future investigations into the use of 2D materials for biomedical applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 6.2
DOI: 10.1016/J.SURFIN.2024.104169
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“Atomic level mechanisms of graphene healing by methane-based plasma radicals”. Khalilov U, Yusupov M, Eshonqulov Gb, Neyts Ec, Berdiyorov Gr, FlatChem 39, 100506 (2023). http://doi.org/10.1016/j.flatc.2023.100506
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.2
DOI: 10.1016/j.flatc.2023.100506
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“Challenges in the electrochemical (bio)sensing of non-electroactive food and environmental contaminants”. Moro G, De Wael K, Moretto LM, Current opinion in electrochemistry 16, 57 (2019). http://doi.org/10.1016/J.COELEC.2019.04.019
Abstract: The electrochemical detection of non-electroactive contaminants can be successfully faced via the use of indirect detection strategies. These strategies can provide sensitive and selective responses often coupled with portable and user-friendly analytical tools. Indirect detection strategies are usually based on the change in the signal of an electroactive probe, induced by the presence of the target molecule at a modified electrode. This critical review aims at addressing the developments in indirect electro-sensing strategies for non-electroactive contaminants in food and environmental analysis in the last years (2017-2019). Emphasis is given to the strategy design, the electrode modifiers used and the feasibility of technological transfer.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Times cited: 4
DOI: 10.1016/J.COELEC.2019.04.019
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“Electrochemical strategies for the detection of forensic drugs”. Florea A, De Jong M, De Wael K, Current opinion in electrochemistry 11, 34 (2018). http://doi.org/10.1016/J.COELEC.2018.06.014
Abstract: Illicit drugs consumption and trafficking is spread worldwide and remains an increasing challenge for local authorities. Forensic drugs and their metabolites are released into wastewaters due to human excretion after illegal consumption of drugs and occasionally due to disposal of clandestine laboratory wastes into sewage systems, being recently classified as the latest group of emerging pollutants. Hence, it is essential to have efficient and accurate methods to detect these type of compounds in seized street samples, biological fluids and wastewaters in order to reduce and prevent trafficking and consumption and negative effects on aquatic systems. Electrochemical strategies offer a fast, portable, low-cost and accurate alternative to chromatographic and spectrometric methods, for the analysis of forensic drugs and metabolites in different matrices. Recent electrochemical strategies applied to the detection of illicit drugs in wastewaters, biological fluids and street samples are presented in this review, together with the impact of drug consumption on the environment.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Times cited: 7
DOI: 10.1016/J.COELEC.2018.06.014
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“Investigating market power in the Belgian pork production chain”. Maes D, Vancauteren M, Van Passel S, Review of Agricultural, Food and Environmental Studies 100, 93 (2019). http://doi.org/10.1007/s41130-019-00096-6
Abstract: Belgian pork production has faced stagnating prices for decades. It remains unclear whether excessive market power from slaughterhouses or meat retailers has played a role in this trend. While market power studies can reveal some of the market dynamics in this setting, this type of research has not yet been applied to the Belgian pork market. The present paper investigates oligopolies and oligopsonies in the pork production sector. We build a new model that focuses on market power dynamics in the market for live pigs and distinguishes horizontal and vertical market power parameters, both for pig farmers and for slaughterhouses. The results follow from an empirical application using unique slaughterhouse data for 2001–2015. The results indicate that the farmers benefit from a significant power advantage in the live pig market, when very modest price demands are taken as a reference. The final market price of live pigs approaches the price requested by the farmers. On the other hand, the measured vertical market power also suggests that a pig farmer does not receive the (modest) full-wage-based salary. The market power of the slaughterhouses is also limited. Market power as a result of collusion—that is, horizontal market power—is present, but is not strong. However, there are significant differences between the slaughterhouses in terms of mark-up on the input prices. These differences reflect differences in company strategy, and this diversity further reduces the possibility to create sector-wide collusive behaviour.
Keywords: A1 Journal Article; Engineering Management (ENM) ;
DOI: 10.1007/s41130-019-00096-6
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“Substrate-induced proximity effect in superconducting niobium nanofilms”. Rezvani SJ, Perali A, Fretto M, De Leo N, Flammia L, Milošević, M, Nannarone S, Pinto N, Condensed Matter 4, 4 (2018). http://doi.org/10.3390/CONDMAT4010004
Abstract: Structural and superconducting properties of high-quality niobium nanofilms with different thicknesses are investigated on silicon oxide (SiO2) and sapphire substrates. The role played by the different substrates and the superconducting properties of the Nb films are discussed based on the defectivity of the films and on the presence of an interfacial oxide layer between the Nb film and the substrate. The X-ray absorption spectroscopy is employed to uncover the structure of the interfacial layer. We show that this interfacial layer leads to a strong proximity effect, especially in films deposited on a SiO2 substrate, altering the superconducting properties of the Nb films. Our results establish that the critical temperature is determined by an interplay between quantum-size effects, due to the reduction of the Nb film thicknesses, and proximity effects. The detailed investigation here provides reference characterizations and has direct and important implications for the fabrication of superconducting devices based on Nb nanofilms.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 3
DOI: 10.3390/CONDMAT4010004
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“Transition metal dichalcogenides as strategy for high temperature electron-hole superfluidity”. Conti S, Neilson D, Peeters FM, Perali A, Condensed Matter 5, 22 (2020). http://doi.org/10.3390/CONDMAT5010022
Abstract: Condensation of spatially indirect excitons, with the electrons and holes confined in two separate layers, has recently been observed in two different double layer heterostructures. High transition temperatures were reported in a double Transition Metal Dichalcogenide (TMD) monolayer system. We briefly review electron-hole double layer systems that have been proposed as candidates for this interesting phenomenon. We investigate the double TMD system WSe2/hBN/MoSe2, using a mean-field approach that includes multiband effects due to the spin-orbit coupling and self-consistent screening of the electron-hole Coulomb interaction. We demonstrate that the transition temperature observed in the double TMD monolayers, which is remarkably high relative to the other systems, is the result of (i) the large electron and hole effective masses in TMDs, (ii) the large TMD band gaps, and (iii) the presence of multiple superfluid condensates in the TMD system. The net effect is that the superfluidity is strong across a wide range of densities, which leads to high transition temperatures that extend as high as TBKT=150 K.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 13
DOI: 10.3390/CONDMAT5010022
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“Effect of mismatched electron-hole effective masses on superfluidity in double layer solid-state systems”. Conti S, Perali A, Peeters FM, Neilson D, Condensed Matter 6, 14 (2021). http://doi.org/10.3390/CONDMAT6020014
Abstract: Superfluidity has been predicted and now observed in a number of different electron-hole double-layer semiconductor heterostructures. In some of the heterostructures, such as GaAs and Ge-Si electron-hole double quantum wells, there is a strong mismatch between the electron and hole effective masses. We systematically investigate the sensitivity to unequal masses of the superfluid properties and the self-consistent screening of the electron-hole pairing interaction. We find that the superfluid properties are insensitive to mass imbalance in the low density BEC regime of strongly-coupled boson-like electron-hole pairs. At higher densities, in the BEC-BCS crossover regime of fermionic pairs, we find that mass imbalance between electrons and holes weakens the superfluidity and expands the density range for the BEC-BCS crossover regime. This permits screening to kill the superfluid at a lower density than for equal masses.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 1
DOI: 10.3390/CONDMAT6020014
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“Enabling hydrate-based methane storage under mild operating conditions by periodic mesoporous organosilica nanotubes”. Beckwee EJ, Watson G, Houlleberghs M, Arenas Esteban D, Bals S, Van Der Voort P, Breynaert E, Martens J, Baron GV, Denayer JFM, Heliyon 9, e17662 (2023). http://doi.org/10.1016/J.HELIYON.2023.E17662
Abstract: Biomethane is a renewable natural gas substitute produced from biogas. Storage of this sustainable energy vector in confined clathrate hydrates, encapsulated in the pores of a host material, is a highly promising avenue to improve storage capacity and energy efficiency. Herein, a new type of periodic mesoporous organosilica (PMO) nanotubes, referred to as hollow ring PMO (HR-PMO), capable of promoting methane clathrate hydrate formation under mild working conditions (273 K, 3.5 MPa) and at high water loading (5.1 g water/g HR-PMO) is reported. Gravimetric uptake measurements reveal a steep single-stepped isotherm and a noticeably high methane storage capacity (0.55 g methane/g HR-PMO; 0.11 g methane/g water at 3.5 MPa). The large working capacity throughout consecutive pressure-induced clathrate hydrate formationdissociation cycles demonstrates the material's excellent recyclability (97% preservation of capacity). Supported by ex situ cryo-electron tomography and x-ray diffraction, HR-PMO nanotubes are hypothesized to promote clathrate hydrate nucleation and growth by distribution and confinement of water in the mesopores of their outer wall, along the central channels of the nanotubes and on the external nanotube surface. These findings showcase the potential for application of organosilica materials with hierarchical and interconnected pore systems for pressure-based storage of biomethane in confined clathrate hydrates.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Times cited: 4
DOI: 10.1016/J.HELIYON.2023.E17662
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“Hydrogen clathrates : next generation hydrogen storage materials”. Gupta A, Baron GV, Perreault P, Lenaerts S, Ciocarlan R-G, Cool P, Mileo PGM, Rogge S, Van Speybroeck V, Watson G, Van Der Voort P, Houlleberghs M, Breynaert E, Martens J, Denayer JFM, Energy Storage Materials 41, 69 (2021). http://doi.org/10.1016/J.ENSM.2021.05.044
Abstract: Extensive research has been carried on the molecular adsorption in high surface area materials such as carbonaceous materials and MOFs as well as atomic bonded hydrogen in metals and alloys. Clathrates stand among the ones to be recently suggested for hydrogen storage. Although, the simulations predict lower capacity than the expected by the DOE norms, the additional benefits of clathrates such as low production and operational cost, fully reversible reaction, environmentally benign nature, low risk of flammability make them one of the most promising materials to be explored in the next decade. The inherent ability to tailor the properties of clathrates using techniques such as addition of promoter molecules, use of porous supports and formation of novel reverse micelles morphology provide immense scope customisation and growth. As rapidly evolving materials, clathrates promise to get as close as possible in the search of “holy grail” of hydrogen storage. This review aims to provide the audience with the background of the current developments in the solid-state hydrogen storage materials, with a special focus on the hydrogen clathrates. The in-depth analysis of the hydrogen clathrates will be provided beginning from their discovery, various additives utilised to enhance their thermodynamic and kinetic properties, challenges in the characterisation of hydrogen in clathrates, theoretical developments to justify the experimental findings and the upscaling opportunities presented by this system. The review will present state of the art in the field and also provide a global picture for the path forward.
Keywords: A1 Journal article; Engineering sciences. Technology; Laboratory of adsorption and catalysis (LADCA); Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.ENSM.2021.05.044
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“Electron pairing: from metastable electron pair to bipolaron”. Hai G-Q, Candido L, Brito BGA, Peeters FM, Journal of physics communications 2, Unsp 035017 (2018). http://doi.org/10.1088/2399-6528/AAAEE0
Abstract: Starting from the shell structure in atoms and the significant correlation within electron pairs, we distinguish the exchange-correlation effects between two electrons of opposite spins occupying the same orbital from the average correlation among many electrons in a crystal. In the periodic potential of the crystal with lattice constant larger than the effective Bohr radius of the valence electrons, these correlated electron pairs can form a metastable energy band above the corresponding single-electron band separated by an energy gap. In order to determine if these metastable electron pairs can be stabilized, we calculate the many-electron exchange-correlation renormalization and the polaron correction to the two-band system with single electrons and electron pairs. We find that the electron-phonon interaction is essential to counterbalance the Coulomb repulsion and to stabilize the electron pairs. The interplay of the electron-electron and electron-phonon interactions, manifested in the exchange-correlation energies, polaron effects, and screening, is responsible for the formation of electron pairs (bipolarons) that are located on the Fermi surface of the single-electron band.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 9
DOI: 10.1088/2399-6528/AAAEE0
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“Suppressing the formation of NOxand N2O in CO2/N2dielectric barrier discharge plasma by adding CH4: scavenger chemistry at work”. Snoeckx R, Van Wesenbeeck K, Lenaerts S, Cha MS, Bogaerts A, Sustainable Energy &, Fuels 3, 1388 (2019). http://doi.org/10.1039/C8SE00584B
Abstract: The need for carbon negative technologies led to the development of a wide array of novel CO<sub>2</sub>conversion techniques. Most of them either rely on high temperatures or generate highly reactive O species, which can lead to the undesirable formation of NO<sub>x</sub>and N<sub>2</sub>O when the CO<sub>2</sub>feeds contain N<sub>2</sub>. Here, we show that, for plasma-based CO<sub>2</sub>conversion, adding a hydrogen source, as a chemical oxygen scavenger, can suppress their formation,<italic>in situ</italic>. This allows the use of low-cost N<sub>2</sub>containing (industrial and direct air capture) feeds, rather than expensive purified CO<sub>2</sub>. To demonstrate this, we add CH<sub>4</sub>to a dielectric barrier discharge plasma used for converting impure CO<sub>2</sub>. We find that when adding a stoichiometric amount of CH<sub>4</sub>, 82% less NO<sub>2</sub>and 51% less NO are formed. An even higher reduction (96 and 63%) can be obtained when doubling this amount. However, in that case the excess radicals promote the formation of by-products, such as HCN, NH<sub>3</sub>and CH<sub>3</sub>OH. Thus, we believe that by using an appropriate amount of chemical scavengers, we can use impure CO<sub>2</sub>feeds, which would bring us closer to ‘real world’ conditions and implementation.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1039/C8SE00584B
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“Single-organoid analysis reveals clinically relevant treatment-resistant and invasive subclones in pancreatic cancer”. Le Compte M, Cardenas De La Hoz E, Peeters S, Rodrigues Fortes F, Hermans C, Domen A, Smits E, Lardon F, Vandamme T, Lin A, Vanlanduit S, Roeyen G, van Laere S, Prenen H, Peeters M, Deben C, npj Precision Oncology 7, 128 (2023). http://doi.org/10.1038/S41698-023-00480-Y
Abstract: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal diseases, characterized by a treatment-resistant and invasive nature. In line with these inherent aggressive characteristics, only a subset of patients shows a clinical response to the standard of care therapies, thereby highlighting the need for a more personalized treatment approach. In this study, we comprehensively unraveled the intra-patient response heterogeneity and intrinsic aggressive nature of PDAC on bulk and single-organoid resolution. We leveraged a fully characterized PDAC organoid panel ( N = 8) and matched our artificial intelligence-driven, live-cell organoid image analysis with retrospective clinical patient response. In line with the clinical outcomes, we identified patient-specific sensitivities to the standard of care therapies (gemcitabine-paclitaxel and FOLFIRINOX) using a growth rate-based and normalized drug response metric. Moreover, the single-organoid analysis was able to detect resistant as well as invasive PDAC organoid clones, which was orchestrates on a patient, therapy, drug, concentration and time-specific level. Furthermore, our in vitro organoid analysis indicated a correlation with the matched patient progression-free survival (PFS) compared to the current, conventional drug response readouts. This work not only provides valuable insights on the response complexity in PDAC, but it also highlights the potential applications (extendable to other tumor types) and clinical translatability of our approach in drug discovery and the emerging era of personalized medicine.
Keywords: A1 Journal article; Center for Oncological Research (CORE); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Antwerp Surgical Training, Anatomy and Research Centre (ASTARC)
DOI: 10.1038/S41698-023-00480-Y
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“Bandgap engineering of two-dimensional semiconductor materials”. Chaves A, Azadani JG, Alsalman H, da Costa DR, Frisenda R, Chaves AJ, Song SH, Kim YD, He D, Zhou J, Castellanos-Gomez A, Peeters FM, Liu Z, Hinkle CL, Oh S-H, Ye PD, Koester SJ, Lee YH, Avouris P, Wang X, Low T, npj 2D Materials and Applications 4, 29 (2020). http://doi.org/10.1038/S41699-020-00162-4
Abstract: Semiconductors are the basis of many vital technologies such as electronics, computing, communications, optoelectronics, and sensing. Modern semiconductor technology can trace its origins to the invention of the point contact transistor in 1947. This demonstration paved the way for the development of discrete and integrated semiconductor devices and circuits that has helped to build a modern society where semiconductors are ubiquitous components of everyday life. A key property that determines the semiconductor electrical and optical properties is the bandgap. Beyond graphene, recently discovered two-dimensional (2D) materials possess semiconducting bandgaps ranging from the terahertz and mid-infrared in bilayer graphene and black phosphorus, visible in transition metal dichalcogenides, to the ultraviolet in hexagonal boron nitride. In particular, these 2D materials were demonstrated to exhibit highly tunable bandgaps, achieved via the control of layers number, heterostructuring, strain engineering, chemical doping, alloying, intercalation, substrate engineering, as well as an external electric field. We provide a review of the basic physical principles of these various techniques on the engineering of quasi-particle and optical bandgaps, their bandgap tunability, potentials and limitations in practical realization in future 2D device technologies.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Times cited: 604
DOI: 10.1038/S41699-020-00162-4
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“Reactive plasma cleaning and restoration of transition metal dichalcogenide monolayers”. Marinov D, de Marneffe J-F, Smets Q, Arutchelvan G, Bal KM, Voronina E, Rakhimova T, Mankelevich Y, El Kazzi S, Nalin Mehta A, Wyndaele P-J, Heyne MH, Zhang J, With PC, Banerjee S, Neyts EC, Asselberghs I, Lin D, De Gendt S, npj 2D Materials and Applications 5, 17 (2021). http://doi.org/10.1038/s41699-020-00197-7
Abstract: The cleaning of two-dimensional (2D) materials is an essential step in the fabrication of future devices, leveraging their unique physical, optical, and chemical properties. Part of these emerging 2D materials are transition metal dichalcogenides (TMDs). So far there is limited understanding of the cleaning of “monolayer” TMD materials. In this study, we report on the use of downstream H<sub>2</sub>plasma to clean the surface of monolayer WS<sub>2</sub>grown by MOCVD. We demonstrate that high-temperature processing is essential, allowing to maximize the removal rate of polymers and to mitigate damage caused to the WS<sub>2</sub>in the form of sulfur vacancies. We show that low temperature in situ carbonyl sulfide (OCS) soak is an efficient way to resulfurize the material, besides high-temperature H<sub>2</sub>S annealing. The cleaning processes and mechanisms elucidated in this work are tested on back-gated field-effect transistors, confirming that transport properties of WS<sub>2</sub>devices can be maintained by the combination of H<sub>2</sub>plasma cleaning and OCS restoration. The low-damage plasma cleaning based on H<sub>2</sub>and OCS is very reproducible, fast (completed in a few minutes) and uses a 300 mm industrial plasma etch system qualified for standard semiconductor pilot production. This process is, therefore, expected to enable the industrial scale-up of 2D-based devices, co-integrated with silicon technology.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1038/s41699-020-00197-7
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“Optical versus electron diffraction imaging of Twist-angle in 2D transition metal dichalcogenide bilayers”. Psilodimitrakopoulos S, Orekhov A, Mouchliadis L, Jannis D, Maragkakis GM, Kourmoulakis G, Gauquelin N, Kioseoglou G, Verbeeck J, Stratakis E, npj 2D Materials and Applications 5, 77 (2021). http://doi.org/10.1038/S41699-021-00258-5
Abstract: Atomically thin two-dimensional (2D) materials can be vertically stacked with van der Waals bonds, which enable interlayer coupling. In the particular case of transition metal dichalcogenide (TMD) bilayers, the relative direction between the two monolayers, coined as twist-angle, modifies the crystal symmetry and creates a superlattice with exciting properties. Here, we demonstrate an all-optical method for pixel-by-pixel mapping of the twist-angle with a resolution of 0.55(degrees), via polarization-resolved second harmonic generation (P-SHG) microscopy and we compare it with four-dimensional scanning transmission electron microscopy (4D STEM). It is found that the twist-angle imaging of WS2 bilayers, using the P-SHG technique is in excellent agreement with that obtained using electron diffraction. The main advantages of the optical approach are that the characterization is performed on the same substrate that the device is created on and that it is three orders of magnitude faster than the 4D STEM. We envisage that the optical P-SHG imaging could become the gold standard for the quality examination of TMD superlattice-based devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Times cited: 4
DOI: 10.1038/S41699-021-00258-5
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“Magnetic order and critical temperature of substitutionally doped transition metal dichalcogenide monolayers”. Tiwari S, Van de Put ML, Sorée B, Vandenberghe WG, npj 2D Materials and Applications 5, 54 (2021). http://doi.org/10.1038/S41699-021-00233-0
Abstract: Using first-principles calculations, we investigate the magnetic order in two-dimensional (2D) transition-metal-dichalcogenide (TMD) monolayers: MoS2, MoSe2, MoTe2, WSe2, and WS2 substitutionally doped with period four transition-metals (Ti, V, Cr, Mn, Fe, Co, Ni). We uncover five distinct magnetically ordered states among the 35 distinct TMD-dopant pairs: the non-magnetic (NM), the ferromagnetic with out-of-plane spin polarization (Z FM), the out-of-plane polarized clustered FMs (clustered Z FM), the in-plane polarized FMs (X-Y FM), and the anti-ferromagnetic (AFM) state. Ni and Ti dopants result in an NM state for all considered TMDs, while Cr dopants result in an anti-ferromagnetically ordered state for all the TMDs. Most remarkably, we find that Fe, Mn, Co, and V result in an FM ordered state for all the TMDs, except for MoTe2. Finally, we show that V-doped MoSe2 and WSe2, and Mn-doped MoS2, are the most suitable candidates for realizing a room-temperature FM at a 16-18% atomic substitution.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
DOI: 10.1038/S41699-021-00233-0
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