“Identifying alternative ferroelectric materials beyond Hf(Zr)O-₂”. Guo J, Clima S, Pourtois G, Van Houdt J, Applied Physics Letters 117, 262903 (2020). http://doi.org/10.1063/5.0028611
Abstract: A database-driven approach combined with ab initio density functional theory (DFT) simulations is used to identify and simulate alternative ferroelectric materials beyond Hf(Zr)O-2. The database-driven screening method identifies a class of wurtzite ferroelectric materials. DFT simulations of wurtzite magnesium chalcogenides, including MgS, MgSe, and MgTe, show their potential to achieve improved ferroelectric (FE) stability, simple atomistic unit cell structure, and large FE polarization. Strain engineering can effectively modulate the FE switching barrier height for facilitating FE switching. The effect of the piezoelectric property on the FE switching barrier heights is also examined.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4
DOI: 10.1063/5.0028611
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“Monolayer 1T-LaN₂, : Dirac spin-gapless semiconductor of p-state and Chern insulator with a high Chern number”. Li L, Kong X, Chen X, Li J, Sanyal B, Peeters FM, Applied Physics Letters 117, 143101 (2020). http://doi.org/10.1063/5.0023531
Abstract: Two-dimensional transition-metal dinitrides have attracted considerable attention in recent years due to their rich magnetic properties. Here, we focus on rare-earth-metal elements and propose a monolayer of lanthanum dinitride with a 1T structural phase, 1T-LaN2. Using first-principles calculations, we systematically investigated the structure, stability, magnetism, and band structure of this material. It is a flexible and stable monolayer exhibiting a low lattice thermal conductivity, which is promising for future thermoelectric devices. The monolayer shows the ferromagnetic ground state with a spin-polarized band structure. Two linear spin-polarized bands cross at the Fermi level forming a Dirac point, which is formed by the p atomic orbitals of the N atoms, indicating that monolayer 1T-LaN2 is a Dirac spin-gapless semiconductor of p-state. When the spin-orbit coupling is taken into account, a large nontrivial indirect bandgap (86/354meV) can be opened at the Dirac point, and three chiral edge states are obtained, corresponding to a high Chern number of C=3, implying that monolayer 1T-LaN2 is a Chern insulator. Importantly, this kind of band structure is expected to occur in more monolayers of rare-earth-metal dinitride with a 1T structural phase.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4
Times cited: 19
DOI: 10.1063/5.0023531
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“2D ferromagnetism at finite temperatures under quantum scrutiny”. Vanherck J, Bacaksiz C, Sorée B, Milošević, MV, Magnus W, Applied Physics Letters 117, 052401 (2020). http://doi.org/10.1063/5.0015619
Abstract: Recent years have seen a tremendous rise of two-dimensional (2D) magnetic materials, several of which were verified experimentally. However, most of the theoretical predictions to date rely on ab initio methods, at zero temperature and fluctuation-free, while one certainly expects detrimental quantum fluctuations at finite temperatures. Here, we present the solution of the quantum Heisenberg model for honeycomb/hexagonal lattices with anisotropic exchange interaction up to third nearest neighbors and in an applied field in arbitrary direction, which answers the question whether long-range magnetization can indeed survive in the ultrathin limit of materials, up to which temperature, and what the characteristic excitation (magnon) frequencies are, all essential to envisaged applications of magnetic 2D materials. We find that long-range magnetic order persists at finite temperature for materials with overall easy-axis anisotropy. We validate the calculations on the examples of monolayers CrI3, CrBr3, and MnSe2. Moreover, we provide an easy-to-use tool to calculate Curie temperatures of new 2D computational materials.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4
Times cited: 8
DOI: 10.1063/5.0015619
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“Substrate dependent terahertz response of monolayer WS₂”. Dong HM, Tao ZH, Li LL, Huang F, Xu W, Peeters FM, Applied Physics Letters 116, 1 (2020). http://doi.org/10.1063/5.0006617
Abstract: We investigate experimentally the terahertz (THz) optoelectronic properties of monolayer (ML) tungsten disulfide (WS2) placed on different substrates using THz time-domain spectroscopy (TDS). We find that the THz optical response of n-type ML WS2 depends sensitively on the choice of the substrate. This dependence is found to be a consequence of substrate induced charge transfer, extra scattering centers, and electronic localization. Through fitting the experimental results with the Drude-Smith formula, we can determine the key sample parameters (e.g., the electronic relaxation time, electron density, and electronic localization factor) of ML WS2 on different substrates. The temperature dependence of these parameters is examined. Our results show that the THz TDS technique is an efficient non-contact method that can be utilized to characterize and investigate the optoelectronic properties of nano-devices based on ML WS2.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4
Times cited: 17
DOI: 10.1063/5.0006617
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“The magnetic, electronic, and light-induced topological properties in two-dimensional hexagonal FeX₂, (X=Cl, Br, I) monolayers”. Kong X, Li L, Liang L, Peeters FM, Liu X-J, Applied Physics Letters 116, 192404 (2020). http://doi.org/10.1063/5.0006446
Abstract: Using Floquet-Bloch theory, we propose to realize chiral topological phases in two-dimensional (2D) hexagonal FeX2 (X=Cl, Br, I) monolayers under irradiation of circularly polarized light. Such 2D FeX2 monolayers are predicted to be dynamically stable and exhibit both ferromagnetic and semiconducting properties. To capture the full topological physics of the magnetic semiconductor under periodic driving, we adopt ab initio Wannier-based tight-binding methods for the Floquet-Bloch bands, with the light-induced bandgap closings and openings being obtained as the light field strength increases. The calculations of slabs with open boundaries show the existence of chiral edge states. Interestingly, the topological transitions with branches of chiral edge states changing from zero to one and from one to two by tuning the light amplitude are obtained, showing that the topological Floquet phase of high Chern number can be induced in the present Floquet-Bloch systems. Published under license by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4
Times cited: 18
DOI: 10.1063/5.0006446
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“Coulomb drag in strongly coupled quantum wells : temperature dependence of the many-body correlations”. Zarenia M, Conti S, Peeters FM, Neilson D, Applied physics letters 115, 202105 (2019). http://doi.org/10.1063/1.5116803
Abstract: We investigate the effect of the temperature dependence of many-body correlations on hole-hole Coulomb drag in strongly coupled GaAs/GaAlAs double quantum wells. For arbitrary temperatures, we obtained the correlations using the classical-map hypernetted-chain approach. We compare the temperature dependence of the resulting drag resistivities rho D(T) at different densities with rho D(T) calculated assuming correlations fixed at zero temperature. Comparing the results with those when correlations are completely neglected, we confirm that correlations significantly increase the drag. We find that the drag becomes sensitive to the temperature dependence of T greater than or similar to 2TF, twice the Fermi temperature. Our results show excellent agreement with available experimental data. Published under license by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 2
DOI: 10.1063/1.5116803
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“Strain engineered linear dichroism and Faraday rotation in few-layer phosphorene”. Li LL, Peeters FM, Applied physics letters 114, 243102 (2019). http://doi.org/10.1063/1.5103172
Abstract: We investigate theoretically the linear dichroism and the Faraday rotation of strained few-layer phosphorene, where strain is applied uniaxially along the armchair or zigzag direction of the phosphorene lattice. We calculate the optical conductivity tensor of uniaxially strained few-layer phosphorene by means of the Kubo formula within the tight-binding approach. We show that the linear dichroism and the Faraday rotation of few-layer phosphorene can be significantly modulated by the applied strain. The modulation depends strongly on both the magnitude and direction of strain and becomes more pronounced with increasing number of phosphorene layers. Our results are relevant for mechano-optoelectronic applications based on optical absorption and Hall effects in strained few-layer phosphorene.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 12
DOI: 10.1063/1.5103172
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“The role of UV photolysis and molecular transport in the generation of reactive species in a tissue model with a cold atmospheric pressure plasma jet”. Ghimire B, Szili EJ, Lamichhane P, Short RD, Lim JS, Attri P, Masur K, Weltmann K-D, Hong S-H, Choi EH, Applied physics letters 114, 093701 (2019). http://doi.org/10.1063/1.5086522
Abstract: Cold atmospheric pressure plasma jets (plasma) operated in ambient air provide a rich source of reactive oxygen and nitrogen species (RONS), which are known to influence biological processes important in disease. In the plasma treatment of diseased tissue such as subcutaneous cancer tumors, plasma RONS need to first traverse an interface between the plasma-skin surface and second be transported to millimeter depths in order to reach deep-seated diseased cells. However, the mechanisms in the plasma generation of RONS within soft tissues are not understood. In this study, we track the plasma jet delivery of RONS into a tissue model target and we delineate two processes: through target delivery of RONS generated (primarily) in the plasma jet and in situ RONS generation by UV photolysis within the target. We demonstrate that UV photolysis promotes the rapid generation of RONS in the tissue model target’s surface after which the RONS are transported to millimeter depths via a slower molecular process. Our results imply that the flux of UV photons from plasma jets is important for delivering RONS through seemingly impenetrable barriers such as skin. The findings have implications not only in treatments of living tissues but also in the functionalization of soft hydrated biomaterials such as hydrogels and extracellular matrix derived tissue scaffolds.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.411
Times cited: 12
DOI: 10.1063/1.5086522
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“Mechanisms for plasma cryogenic etching of porous materials”. Zhang Q-Z, Tinck S, de Marneffe J-F, Zhang L, Bogaerts A, Applied physics letters 111, 173104 (2017). http://doi.org/10.1063/1.4999439
Abstract: Porous materials are commonly used in microelectronics, as they can meet the demand for continuously shrinking electronic feature dimensions. However, they are facing severe challenges in plasma etching, due to plasma induced damage. In this paper, we present both the plasma characteristics and surface processing during the etching of porous materials. We explain how the damage occurs in the porous material during plasma etching for a wide range of chuck temperatures and the responsible mechanism for plasma damage-free etching at cryogenic temperature, by a combination of experiments and numerical modeling.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.411
Times cited: 2
DOI: 10.1063/1.4999439
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“Electron Bessel beam diffraction for precise and accurate nanoscale strain mapping”. Guzzinati G, Ghielens W, Mahr C, Béché, A, Rosenauer A, Calders T, Verbeeck J, Applied physics letters 114, 243501 (2019). http://doi.org/10.1063/1.5096245
Abstract: Strain has a strong effect on the properties of materials and the performance of electronic devices. Their ever shrinking size translates into a constant demand for accurate and precise measurement methods with a very high spatial resolution. In this regard, transmission electron microscopes are key instruments thanks to their ability to map strain with a subnanometer resolution. Here, we present a method to measure strain at the nanometer scale based on the diffraction of electron Bessel beams. We demonstrate that our method offers a strain sensitivity better than 2.5 × 10−4 and an accuracy of 1.5 × 10−3, competing with, or outperforming, the best existing methods with a simple and easy to use experimental setup.
Keywords: A1 Journal article; ADReM Data Lab (ADReM); Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 17
DOI: 10.1063/1.5096245
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“Spectroscopic coincidence experiments in transmission electron microscopy”. Jannis D, Müller-Caspary K, Béché, A, Oelsner A, Verbeeck J, Applied physics letters 114, 143101 (2019). http://doi.org/10.1063/1.5092945
Abstract: We demonstrate the feasibility of coincidence measurements on a conventional transmission electron microscope, revealing the temporal
correlation between electron energy loss spectroscopy (EELS) and energy dispersive X-ray (EDX) spectroscopy events. We make use of a
delay line detector with ps-range time resolution attached to a modified EELS spectrometer. We demonstrate that coincidence between both
events, related to the excitation and deexcitation of atoms in a crystal, provides added information not present in the individual EELS or
EDX spectra. In particular, the method provides EELS with a significantly suppressed or even removed background, overcoming the many
difficulties with conventional parametric background fitting as it uses no assumptions on the shape of the background, requires no user input
and does not suffer from counting noise originating from the background signal. This is highly attractive, especially when low concentrations
of elements need to be detected in a matrix of other elements.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 18
DOI: 10.1063/1.5092945
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“Overcoming contrast reversals in focused probe ptychography of thick materials: An optimal pipeline for efficiently determining local atomic structure in materials science”. Gao C, Hofer C, Jannis D, Béché, A, Verbeeck J, Pennycook TJ, Applied physics letters 121, 081906 (2022). http://doi.org/10.1063/5.0101895
Abstract: Ptychography provides highly efficient imaging in scanning transmission electron microscopy (STEM), but questions have remained over its applicability to strongly scattering samples such as those most commonly seen in materials science. Although contrast reversals can appear in ptychographic phase images as the projected potentials of the sample increase, we show here how these can be easily overcome by a small amount of defocus. The amount of defocus is small enough that it not only can exist naturally when focusing using the annular dark field (ADF) signal but can also be adjusted post acquisition. The ptychographic images of strongly scattering materials are clearer at finite doses than other STEM techniques and can better reveal light atomic columns within heavy lattices. In addition, data for ptychography can now be collected simultaneously with the fastest of ADF scans. This combination of sensitivity and interpretability presents an ideal workflow for materials science.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4
Times cited: 9
DOI: 10.1063/5.0101895
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“Metal-insulator transition of SrVO 3 ultrathin films embedded in SrVO 3 / SrTiO 3 superlattices”. Wang J, Gauquelin N, Huijben M, Verbeeck J, Rijnders G, Koster G, Applied Physics Letters 117, 133105 (2020). http://doi.org/10.1063/5.0020615
Abstract: The metal-insulator transition (MIT) in strongly correlated oxides is a topic of great interest for its potential applications, such as Mott field effect transistors and sensors. We report that the MIT in high quality epitaxial SrVO3 (SVO) thin films is present as the film thickness is reduced, lowering the dimensionality of the system, and electron-electron correlations start to become the dominant interactions. The critical thickness of 3 u.c is achieved by avoiding effects due to off-stoichiometry using optimal growth conditions and excluding any surface effects by a STO capping layer. Compared to the single SVO thin films, conductivity enhancement in SVO/STO superlattices is observed. This can be explained by the interlayer coupling effect between SVO sublayers in the superlattices. Magnetoresistance and Hall measurements indicate that the dominant driving force of MIT is the electron–electron interaction.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4
Times cited: 8
DOI: 10.1063/5.0020615
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“Development of a fast electromagnetic beam blanker for compressed sensing in scanning transmission electron microscopy”. Béché, A, Goris B, Freitag B, Verbeeck J, Applied physics letters 108, 093103 (2016). http://doi.org/10.1063/1.4943086
Abstract: The concept of compressed sensing was recently proposed to significantly reduce the electron dose in scanning transmission electron microscopy (STEM) while still maintaining the main features in the image. Here, an experimental setup based on an electromagnetic beam blanker placed in the condenser plane of a STEM is proposed. The beam blanker deflects the beam with a random pattern, while the scanning coils are moving the beam in the usual scan pattern. Experimental images at both the medium scale and high resolution are acquired and reconstructed based on a discrete cosine algorithm. The obtained results confirm that compressed sensing is highly attractive to limit beam damage in experimental STEM even though some remaining artifacts need to be resolved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 40
DOI: 10.1063/1.4943086
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“Stable half-metallic monolayers of FeCl2”. Torun E, Sahin H, Singh SK, Peeters FM, Applied physics letters 106, 192404 (2015). http://doi.org/10.1063/1.4921096
Abstract: The structural, electronic, and magnetic properties of single layers of Iron Dichloride (FeCl2) were calculated using first principles calculations. We found that the 1T phase of the single layer FeCl2 is 0.17 eV/unit cell more favorable than its 1H phase. The structural stability is confirmed by phonon calculations. We found that 1T-FeCl2 possess three Raman-active (130, 179, and 237 cm(-1)) and one infrared-active (279 cm(-1)) phonon branches. The electronic band dispersion of the 1T-FeCl2 is calculated using both gradient approximation of Perdew-Burke-Ernzerhof and DFT-HSE06 functionals. Both functionals reveal that the 1T-FeCl2 has a half-metallic ground state with a Curie temperature of 17 K. (C) 2015 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 84
DOI: 10.1063/1.4921096
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“Integrated atomistic chemical imaging and reactive force field molecular dynamic simulations on silicon oxidation”. Dumpala S, Broderick SR, Khalilov U, Neyts EC, van Duin ACT, Provine J, Howe RT, Rajan K, Applied physics letters 106, 011602 (2015). http://doi.org/10.1063/1.4905442
Abstract: In this paper, we quantitatively investigate with atom probe tomography, the effect of temperature on the interfacial transition layer suboxide species due to the thermal oxidation of silicon. The chemistry at the interface was measured with atomic scale resolution, and the changes in chemistry and intermixing at the interface were identified on a nanometer scale. We find an increase of suboxide (SiOx) concentration relative to SiO2 and increased oxygen ingress with elevated temperatures. Our experimental findings are in agreement with reactive force field molecular dynamics simulations. This work demonstrates the direct comparison between atom probe derived chemical profiles and atomistic-scale simulations for transitional interfacial layer of suboxides as a function of temperature.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.411
Times cited: 19
DOI: 10.1063/1.4905442
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