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“Cubic lead perovskite PbMoO3 with anomalous metallic behavior”. Takatsu H, Hernandez O, Yoshimune W, Prestipino C, Yamamoto T, Tassel C, Kobayashi Y, Batuk D, Shibata Y, Abakumov AM, Brown CM, Kageyama H, Physical review B 95, 155105 (2017). http://doi.org/10.1103/PHYSREVB.95.155105
Abstract: A previously unreported Pb-based perovskite PbMoO3 is obtained by high-pressure and high-temperature synthesis. This material crystallizes in the Pm3m cubic structure at room temperature, making it distinct from typical Pb-based perovskite oxides with a structural distortion. PbMoO3 exhibits a metallic behavior down to 0.1 K with an unusual T-sublinear dependence of the electrical resistivity. Moreover, a large specific heat is observed at low temperatures accompanied by a peak in C-P/T-3 around 10 K, in marked contrast to the isostructural metallic system SrMoO3. These transport and thermal properties for PbMoO3, taking into account anomalously large Pb atomic displacements detected through diffraction experiments, are attributed to a low-energy vibrational mode, associated with incoherent off-centering of lone-pair Pb2+ cations. We discuss the unusual behavior of the electrical resistivity in terms of a polaronlike conduction, mediated by the strong coupling between conduction electrons and optical phonons of the local low-energy vibrational mode.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1103/PHYSREVB.95.155105
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“Improving footprint calculations of small open economies : combining local with multi-regional input-output tables”. Christis M, Geerken T, Vercalsteren A, Vrancken KCM, Economic systems research 29, 25 (2017). http://doi.org/10.1080/09535314.2016.1245653
Abstract: In a small, open and resource-poor economy, import and export dependency have an ever-growing impact on local policy decisions, which makes local (environmental) policy-makers increasingly depend on global data. This increases the interest in models that link local production and consumption data to global production, trade and environmental data. The recent increase in availability of global environmentally extended multi-regional input-output tables (EE-MRIO tables) provides an opportunity to link them with existing local environmentally extended input-output tables (EE-RIO tables). These combined tables make it possible (1) to analyse the links between local and global production and consumption and (2) to study global value chains, material use and environmental impacts simultaneously. However, estimations using input-output (I-O) analyses contain errors due to imperfect databases. In this article the magnitude of specification, aggregation and time errors are estimated and compared. The results show the need to combine local datasets with multi-regional ones and show that highest detailed (country and sector levels) as well as time series of I-O tables are the way forward for using I-O analyses in local policy-making. The paper provides guidance on trading off investments in model adoption and/or extension and the reliability of estimation results.
Keywords: A1 Journal article; Economics; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1080/09535314.2016.1245653
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“Young people's acceptance of bioenergy and the influence of attitude strength on information provision”. Van Dael M, Lizin S, Swinnen G, Van Passel S, Renewable Energy 107, 417 (2017). http://doi.org/10.1016/J.RENENE.2017.02.010
Abstract: This study investigated the effects of using a standardized PowerPoint lecture to provide young people with nuanced information about bioenergy. The studys aim was to understand the relationship between knowledge and participants perception of bioenergy, and the relationship of the latter to participants attitude strength and intention to use and learn about bioenergy. Data were collected from 715 participants using a survey instrument that contained mainly Likert-scale questions. Data were then processed using partial least squares structural equation modelling. Results show that providing such information increases knowledge about bioenergy, but does relatively little to create a more positive perception of bioenergy. In turn, having a more positive view about bioenergy would lead to a higher intention to use bioenergy. Attitude strength was found to mediate the previous relationship and decreases the strength of the relationship between perception and intention to use. Results also show that the lecture weakly contributed to building attitude strength, rendering opinion change less likely in the future. We conclude that listening to a lecture on bioenergy slightly improves peoples perception of bioenergy, makes it more likely that people maintain such a disposition, and translates into a slightly higher intention to use bioenergy.
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 4.357
Times cited: 10
DOI: 10.1016/J.RENENE.2017.02.010
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“A systematic review of environmental and economic impacts of smart grids”. Moretti M, Njakou Djomo S, Azadi H, May K, De Vos K, Van Passel S, Witters N, Renewable &, Sustainable Energy Reviews 68, 888 (2017). http://doi.org/10.1016/J.RSER.2016.03.039
Abstract: Smart grids (SGs) have a central role in the development of the global power sector. Cost-benefit analyses and environmental impact assessments are used to support policy on the deployment of SG systems and technologies. However, the conflicting and widely varying estimates of costs, benefits, greenhouse gas (GHG) emission reduction, and energy savings in literature leave policy makers struggling with how to advise regarding SG deployment. Identifying the causes for the wide variation of individual estimates in the literature is crucial if evaluations are to be used in decision-making. This paper (i) summarizes and compares the methodologies used for economic and environmental evaluation of SGs (ii) identifies the sources of variation in estimates across studies, and (iii) point to gap in research on economic and environmental analyses of SG systems. Seventeen studies (nine articles and eight reports published between 2000 and 2015) addressing the economic costs versus benefits, energy efficiency, and GHG emissions of SGs were systematically searched, located, selected, and reviewed. Their methods and data were subsequently extracted and analysed. The results show that no standardized method currently exists for assessing the economic and environmental impacts of SG systems. The costs varied between 0.03 and 1143 M/yr, while the benefits ranged from 0.04 to 804 M/yr, suggesting that SG systems do not result in cost savings The primary energy savings ranged from 0.03 to 0.95 MJ/kWh, whereas the GHG emission reduction ranged from 10 to 180 gCO2/kWh, depending on the country grid mix and the system boundary of the SG system considered. The findings demonstrate that although SG systems are energy efficient and reduce GHG emissions, investments in SG systems may not yield any benefits. Standardizing some methodologies and assumptions such as discount rates, time horizon and scrutinizing some key input data will result in more consistent estimates of costs and benefits, GHG emission reduction, and energy savings.
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 8.05
Times cited: 27
DOI: 10.1016/J.RSER.2016.03.039
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“A review of the sustainability of algal-based biorefineries : towards an integrated assessment framework”. Thomassen G, Van Dael M, Lemmens B, Van Passel S, Renewable &, Sustainable Energy Reviews 68, 876 (2017). http://doi.org/10.1016/J.RSER.2016.02.015
Abstract: Algal-based bioenergy products have faced multiple economic and environmental problems. To counter these problems, algal-based biorefineries have been proposed as a promising solution. Multiple environmental and economic assessments have analyzed this concept. However, a wide variation in results was reported. This study performs a review to evaluate the methodological reasons behind this variation. Based on this review, four main challenges for a sustainability assessment were identified: 1) the use of a clear framework; 2) the adaptation of the methodology to all stages of technological maturity; 3) the use of harmonized assumptions; 4) the integration of the technological process. A generic methodology, based on the integration of a techno-economic assessment methodology and a streamlined life cycle assessment was proposed. This environmental techno-economic assessment can be performed following an iterative approach during each stage of technology development. In this way, crucial technological parameters can be directly identified and evaluated during the maturation of the technology. The use of this assessment methodology can therefore act as guidance to decrease the time-to-market for innovative and sustainable technologies.
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 8.05
Times cited: 23
DOI: 10.1016/J.RSER.2016.02.015
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“Estimating human health impacts and costs due to Iranian fossil fuel power plant emissions through the impact pathway approach”. Jorli M, Van Passel S, Sadeghi H, Nasseri A, Agheli L, Energies 10, 2136 (2017). http://doi.org/10.3390/EN10122136
Abstract: Air pollutants from fossil fuel fired power plants harm the environment and human health. More than 91% of Irans electricity production is from thermal power plants that use natural gas, diesel, and fuel oil. We apply the impact pathway approach to estimate the health impacts arising from Iranian fossil-based electricity generation emission, and in a next step, we calculate monetary costs of the estimated damages, for a one-year period starting from 20 March 2016 through 2017. We use the new version of SIMPACTS (International Atomic Energy Agency, Vienna, Austria) to investigate the health effects from 61 major Iran fossil-based power plants separately. The selected plants represent 95.6% of total Iran fossil-based power generation. Using the individual and different power plant estimates, we avoid extrapolation and our results can be considered more reliable, taking into account spatial differences. The total damage cost is 723.42 million USD (2000). The damage cost per generated electricity varies from 0.06 to 22.41 USD/MWh and average plant damage cost is 2.85 USD/MWh. Accounting for these external costs indicates the actual costs of fossil energy. The results are useful for policy makers to compare the health costs from these plants and to decide on cleaner energy sources and to take measures to increase benefits for society.
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 2.262
Times cited: 4
DOI: 10.3390/EN10122136
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“Land-use suitability in Northeast Iran : application of AHP-GIS hybrid model”. Memarbashi E, Azadi H, Barati AA, Mohajeri F, Van Passel S, Witlox F, Isprs International Journal Of Geo-Information 6, 396 (2017). http://doi.org/10.3390/IJGI6120396
Abstract: Land-use suitability is the ability of a given type of land to support a defined use. Analysis of land-use suitability requires the consideration of a variety of criteria, not only the natural/physical capacity of a land unit, but also its socioeconomic and environmental impact implications. As land suitability is assessed within a Geographic Information System (GIS) environment, it is formulated as a multi-criteria decision making (MCDM) problem. The study was conducted in the Sangab Plain in northeast Iran. We investigated the study areas suitability for grassland and agricultural uses. A hybrid method of the analytic hierarchy process (AHP) and GIS methodology was applied to evaluate land suitability based on a set of criteria and sub-criteria. Results showed that 20% of the study area had high (rich), 65% had medium (fair), and 15% had low (poor) suitability for agriculture. In terms of grassland use, the comparable amounts were, respectively, about 7%, 23%, and 70%. The lands of the Sangab Plain have medium potential for agricultural use and low potential for grassland use. This paper used both qualitative and quantitative techniques.
Keywords: A1 Journal article; Economics; Engineering Management (ENM); Government and Law
Impact Factor: 0.371
Times cited: 7
DOI: 10.3390/IJGI6120396
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“A Ricardian analysis of the impact of climate change on European agriculture”. Van Passel S, Massetti E, Mendelsohn R, Environmental &, Resource Economics 67, 725 (2017). http://doi.org/10.1007/S10640-016-0001-Y
Abstract: This research estimates the impact of climate on European agriculture using a continental scale Ricardian analysis. Climate, soil, geography and regional socio-economic variables are matched with farm level data from 41,030 farms across Western Europe. We demonstrate that a median quantile regression outperforms OLS given farm level data. The results suggest that European farms are slightly more sensitive to warming than American farms with impacts from +5 to −32 % by 2100 depending on the climate scenario. Farms in Southern Europe are predicted to be particularly sensitive, suffering losses of −5 to −9 % per degree Celsius.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 1.582
Times cited: 15
DOI: 10.1007/S10640-016-0001-Y
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“Organic farming and small-scale farmers : main opportunities and challenges”. Jouzi Z, Azadi H, Taheri F, Zarafshani K, Gebrehiwot K, Van Passel S, Lebailly P, Ecological Economics 132, 144 (2017). http://doi.org/10.1016/J.ECOLECON.2016.10.016
Abstract: Producing enough food to meet the needs of a growing population has always been the greatest concern of food policy-makers around the world. Given the increasing attention to organic farming (OF), we conducted this study to investigate the main opportunities and challenges of the food production system of small-scale farmers in developing countries with an emphasis on their livelihoods. The study showed that the most significant advantages of OF are environmental protection and a higher resilience to environmental changes, increasing farmers' income and reducing external input cost, enhancing social capacity and increasing employment opportunities. A s well as enhancing food security primarily by increasing the food purchasing power of local people. However, the main challenges of this food production system include lower yields in comparison to conventional systems, difficulties with soil nutrient management, certification and market barriers, and the educational and research needs of small-holders. The paper concludes that even though OF might present some significant challenges to small-scale farmers, it could/should still be considered as a part of the solution and means of improving their livelihoods.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 2.965
Times cited: 39
DOI: 10.1016/J.ECOLECON.2016.10.016
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“Monetary valuation of natural predators for biological pest control in pear production”. Daniels S, Witters N, Beliën T, Vrancken K, Vangronsveld J, Van Passel S, Ecological Economics 134, 160 (2017). http://doi.org/10.1016/J.ECOLECON.2016.12.029
Abstract: In spite of global actions, biodiversity is declining at an alarming rate. Despite the need for objectively comparable monetary standards to include biodiversity arguments in policymaking, research on the relationship between species diversity and its valuation from a societal perspective is still scarce. In this paper, a methodological framework for the valuation of natural predators based on their ecological role in the agroecosystem is introduced. The framework integrates a dynamic ecological model simulating interactions between species with an economic model, thereby quantifying the effect of reduced numbers of natural predators on the net farm income. The model attributes an objective monetary value to increased species diversity through the changes in the provisioning of a marketable good. Results indicate that the loss of three predators could decrease net farm income with 88.86 ha− 1 to 2186.5 ha− 1. For the pear production sector in Flanders in 2011, this constitutes to an indirect use value of 0,68 million for one predator and 16.63 million for the presence of three predators. The aim is to provide a justification for the argument for biodiversity conservation, based on the ecological function of species, through the delivery of comparable monetary standards.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 2.965
Times cited: 4
DOI: 10.1016/J.ECOLECON.2016.12.029
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“Impacts of the Hara biosphere reserve on livelihood and welfare in Persian Gulf”. Pour MD, Motiee N, Barati AA, Taheri F, Azadi H, Gebrehiwot K, Lebailly P, Van Passel S, Witlox F, Ecological Economics 141, 76 (2017). http://doi.org/10.1016/J.ECOLECON.2017.05.023
Abstract: Despite the importance of biosphere reserves in Iran's livelihood and welfare, the economic significance of Hara Biosphere Reserve has never been comprehensively studied. This study examines the current importance of Hara Biosphere Reserve (HBR) in local livelihood and welfare. Using a household survey, data were collected through a questionnaire, key informant interviews and direct observations. Two hundred and forty-four households were randomly selected from 10 villages through proportional sampling. Results showed that non-environmental income was the first driver of the total income, poverty alleviation and narrowing income inequality gap. Park income was the second. The results also showed that excluding park income from total income would significantly increase headcount poverty, widen the poverty gap, and raise the Gini coefficient. Wealthier households had the greatest absolute income from the environment, including forest, fishing and fodder. However, the poorest group had smallest absolute income from these sources. Thus, the study demonstrated that wealthier households are responsible for the overharvesting of environmental resources. Interestingly, the study showed that wealthier households are more dependent on profitable environmental incomes sources while the poorest are more dependent on non-profitable ones. (C) 2017 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 2.965
Times cited: 7
DOI: 10.1016/J.ECOLECON.2017.05.023
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“Heterogeneous impact of soil contamination on farmland prices in the Belgian Campine region : evidence from unconditional quantile regressions”. Peeters L, Schreurs E, Van Passel S, Environmental &, Resource Economics 66, 135 (2017). http://doi.org/10.1007/S10640-015-9945-6
Abstract: We estimate a hedonic-pricing model using geo-coded farmland-transaction data from the Campine region, situated in the north-east of Belgium. Unlike previous hedonic studies, we use the method of unconditional quantile regression (Firpo et al., in Econometrica 77(3):953973, 2009). An important advantage of this new method over the traditional conditional quantile regression (Koenker and Bassett, in Econometrica 46(1):3350, 1978) is that it allows for the estimation of potentially heterogeneous effects of cadmium pollution along the entire (unconditional) distribution of farmland prices. Using a threshold specification of the hedonic-pricing model, we find evidence of a U-shaped valuation pattern, where cadmium pollution of the soil has a negative and significant impact on prices only in the middle range of the distribution, insofar as cadmium concentrations are above the regulatory standard of 2 parts per million for agricultural land. Results obtained from a probit model to classify land plots into different price segments further suggest that the heterogeneous impact of soil pollution on price can be directly related to the variety of amenities that farmland provides.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 1.582
Times cited: 4
DOI: 10.1007/S10640-015-9945-6
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“Environmental and health impacts of effluents from textile industries in Ethiopia : the case of Gelan and Dukem, Oromia Regional State”. Dadi D, Stellmacher T, Senbeta F, Van Passel S, Azadi H, Environmental Monitoring And Assessment 189, 11 (2017). http://doi.org/10.1007/S10661-016-5694-4
Abstract: This study focuses on four textile industries (DH-GEDA, NOYA, ALMHADI, and ALSAR) established between 2005 and 2008 in the peri-urban areas of Dukem and Gelan. The objectives of the study were to generate baseline information regarding the concentration levels of selected pollutants and to analyze their effects on biophysical environments. This study also attempts to explore the level of exposure that humans and livestock have to polluted effluents and the effects thereof. The findings of this study are based on data empirically collected from two sources: laboratory analysis of sample effluents from the four selected textile plants and quantitative as well as qualitative socioeconomic data collection. As part of the latter, a household survey and focus group discussions (FGDs) with elderly and other focal persons were employed in the towns of Dukem and Gelan. The results of the study show that large concentrations of biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), and pH were found in all the observed textile industries, at levels beyond the permissible discharge limit set by the national Environmental Protection Authority (EPA). Furthermore, sulfide (S2), R-phosphate (R-PO43), and Zn were found in large concentrations in DH-GEDA and ALMHADI, while high concentrations were also identified in samples taken from ALSAR and ALMHADI. In spite of the clear-cut legal tools, this study shows that the local environment, people, and their livestock are exposed to highly contaminated effluents. We therefore recommend that the respective federal and regional government bodies should reexamine the compliance to and actual implementation of the existing legal procedures and regulations and respond appropriately.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 1.687
Times cited: 6
DOI: 10.1007/S10661-016-5694-4
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“Canola adoption enhancement in Western Iran”. Zarafshani K, Ghasemi S, Houshyar E, Ghanbari R, Van Passel S, Azadi H, Journal Of Agricultural Science And Technology 19, 47 (2017)
Abstract: Canola production is an important alternative for agricultural policy-makers in Iran to reduce dependency on the imported vegetable oils. Nevertheless, the canola planted area is only increasing at a slow pace, indicating a low willingness-to-accept of farmers. The general aim of this study was to determine the factors influencing the canola adoption in the Kermanshah Province in Western Iran. Employing stratified random sampling method, 106 farmers from each adopter and non-adopter group were selected. Helping to reach a suitable extensional program, two main categories of variables were defined; i.e. farmers personal characteristics and extension parameters. The analysis of farmers personal characteristics variables revealed that the adopters had larger farms and were younger. The results also show that 80% of the adopters were highly to very highly willing to cultivate canola. Furthermore, a logistic regression model estimated the influence of extensional parameters variables on the canola adoption. According to the regression model, the most effective factors are contact with extension agents and participating in extension classes. As a conclusion, it is suggested that the focus of extension services should be to reduce the distance to agricultural service centers in combination with more contact with extension agents and classes.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 0.813
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“Battery pack recycling : behaviour change interventions derived from an integrative theory of planned behaviour study”. Lizin S, Van Dael M, Van Passel S, Van Dael M, Resources Conservation And Recycling 122, 66 (2017). http://doi.org/10.1016/J.RESCONREC.2017.02.003
Abstract: Belgium has passed the 45% cap, mandated by the European Union, by achieving a collection rate of over 50% in 2012. Having such a collection rate, Belgium is amongst the frontrunners in battery recycling in Europe. However, despite the efforts, about 40% of used batteries are still not properly collected. Particularly troublesome according to the national producer responsibility organization are the battery packs. In this paper we therefore investigate the drivers and barriers to battery pack drop-off intention perceived by Belgian households using an integrative model based on the Theory of Planned Behaviour. An R2 of 0.64 was found, which according to the literature on partial least squares structural equation modelling signals a moderate yet very close to substantial coefficient of determination. We find that on average perceived behavioural control and moral norms have the largest influence on the intention to drop-off used battery packs as quickly as possible. Based on the insights gained, recommendations are made for both behaviour change interventions and future research.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 3.313
Times cited: 21
DOI: 10.1016/J.RESCONREC.2017.02.003
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“Sulfur-alloyed Cr2O3: a new p-type transparent conducting oxide host”. Dabaghmanesh S, Saniz R, Neyts E, Partoens B, RSC advances 7, 4453 (2017). http://doi.org/10.1039/C6RA27852C
Abstract: Doped Cr2O3 has been shown to be a p-type transparent conducting oxide (TCO). Its conductivity, however, is low. As for most p-type TCOs, the main problem is the high effective hole mass due to flat valence bands. We use first-principles methods to investigate whether one can increase the valence band dispersion (i.e. reduce the hole mass) by anion alloying with sulfur, while keeping the band gap large enough for transparency. The alloying concentrations considered are given by Cr(4)SxO(6-x), with x = 1-5. To be able to describe the electronic properties of these materials accurately, we first study Cr2O3, examining critically the accuracy of different density functionals and methods, including PBE, PBE+U, HSE06, as well as perturbative approaches within the GW approximation. Our results demonstrate that Cr4S2O4 has an optical band gap of 3.08 eV and an effective hole mass of 1.8 m(e). This suggests Cr4S2O4 as a new p-type TCO host candidate.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.108
Times cited: 9
DOI: 10.1039/C6RA27852C
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“A first principles study of p-type defects in LaCrO3”. Dabaghmanesh S, Sarmadian N, Neyts EC, Partoens B, Physical chemistry, chemical physics 19, 22870 (2017). http://doi.org/10.1039/C7CP03575F
Abstract: Recently, Sr-doped LaCrO3 has been experimentally introduced as a new p-type transparent conducting oxide. It is demonstrated that substituting Sr for La results in inducing p-type conductivity in LaCrO3. Performing first principles calculations we study the electronic structure and formation energy of various point defects in LaCrO3. Our results for the formation energies show that in addition to Sr, two more divalent defects, Ca and Ba, substituting for La in LaCrO3, behave as shallow acceptors in line with previous experimental reports. We further demonstrate that under oxygen-poor growth conditions, these shallow acceptors will be compensated by intrinsic donor-like defects (an oxygen vacancy and Cr on an oxygen site), but in the oxygen-rich growth regime the shallow acceptors have the lowest formation energies between all considered defects and will lead to p-type conductivity.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.123
Times cited: 16
DOI: 10.1039/C7CP03575F
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“The formation of Cr2O3 nanoclusters over graphene sheet and carbon nanotubes”. Dabaghmanesh S, Neek-Amal M, Partoens B, Neyts EC, Chemical physics letters 687, 188 (2017). http://doi.org/10.1016/J.CPLETT.2017.09.005
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.815
Times cited: 2
DOI: 10.1016/J.CPLETT.2017.09.005
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“Paths to collapse for isolated skyrmions in few-monolayer ferromagnetic films”. Stosic D, Mulkers J, Van Waeyenberge B, Ludermir TB, Milošević, MV, Physical review B 95, 214418 (2017). http://doi.org/10.1103/PhysRevB.95.214418
Abstract: Magnetic skyrmions are topological spin configurations in materials with chiral Dzyaloshinskii-Moriya interaction (DMI), that are potentially useful for storing or processing information. To date, DMI has been found in few bulk materials, but can also be induced in atomically thin magnetic films in contact with surfaces with large spin-orbit interactions. Recent experiments have reported that isolated magnetic skyrmions can be stabilized even near room temperature in few-atom-thick magnetic layers sandwiched between materials that provide asymmetric spin-orbit coupling. Here we present the minimum-energy path analysis of three distinct mechanisms for the skyrmion collapse, based on ab initio input and the performed atomic-spin simulations. We focus on the stability of a skyrmion in three atomic layers of Co, either epitaxial on the Pt(111) surface or within a hybrid multilayer where DMI nontrivially varies per monolayer due to competition between different symmetry breaking from two sides of the Co film. In laterally finite systems, their constrained geometry causes poor thermal stability of the skyrmion toward collapse at the boundary, which we show to be resolved by designing the high-DMI structure within an extended film with lower or no DMI.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 48
DOI: 10.1103/PhysRevB.95.214418
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“Application of the weighted-density approximation to the accurate description of electron-positron correlation effects in materials”. Callewaert V, Saniz R, Barbiellini B, Bansil A, Partoens B, Physical review B 96, 085135 (2017). http://doi.org/10.1103/PhysRevB.96.085135
Abstract: We discuss positron-annihilation lifetimes for a set of illustrative bulk materials within the framework of the weighted-density approximation (WDA). The WDA can correctly describe electron-positron correlations in strongly inhomogeneous systems, such as surfaces, where the applicability of (semi-)local approximations is limited. We analyze the WDA in detail and show that the electrons which cannot screen external charges efficiently, such as the core electrons, cannot be treated accurately via the pair correlation of the homogeneous electron gas. We discuss how this problem can be addressed by reducing the screening in the homogeneous electron gas by adding terms depending on the gradient of the electron density. Further improvements are obtained when core electrons are treated within the LDA and the valence electron using the WDA. Finally, we discuss a semiempirical WDA-based approach in which a sum rule is imposed to reproduce the experimental lifetimes.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 6
DOI: 10.1103/PhysRevB.96.085135
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“Surface states and positron annihilation spectroscopy: results and prospects from a first-principles approach”. Callewaert V, Saniz R, Barbiellini B, Partoens B, Journal of physics : conference series 791, 012036 (2017). http://doi.org/10.1088/1742-6596/791/1/012036
Abstract: The trapping of positrons at the surface of a material can be exploited to study quite selectively the surface properties of the latter by means of positron annihilation spectroscopy techniques. To support these, it is desirable to be able to theoretically predict the existence of such positronic surface states and to describe their annihilation characteristics with core or valence surface electrons in a reliable way. Here, we build on the well-developed first-principles techniques for the study of positrons in bulk solids as well as on previous models for surfaces, and investigate two schemes that can improve the theoretical description of the interaction of positrons with surfaces. One is based on supplementing the local-density correlation potential with the corrugated image potential at the surface, and the other is based on the weighted-density approximation to correlation. We discuss our results for topological insulators, graphene layers, and quantum dots, with emphasis on the information that can be directly related to experiment. We also discuss some open theoretical problems that should be addressed by future research.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 1
DOI: 10.1088/1742-6596/791/1/012036
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“New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy”. Eijt SWH, Shi W, Mannheim A, Butterling M, Schut H, Egger W, Dickmann M, Hugenschmidt C, Shakeri B, Meulenberg RW, Callewaert V, Saniz R, Partoens B, Barbiellini B, Bansil A, Melskens J, Zeman M, Smets AHM, Kulbak M, Hodes G, Cahen D, Brück E, Journal of physics : conference series 791, 012021 (2017). http://doi.org/10.1088/1742-6596/791/1/012021
Abstract: Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their surface composition and electronic structure. Further, 2D-Angular Correlation of Annihilation Radiation (2D-ACAR) is used to investigate the nanostructure of divacancies in photovoltaic-high-quality a-Si:H films. The collected momentum distributions were converted by Fourier transformation to the direct space representation of the electron-positron autocorrelation function. The evolution of the size of the divacancies as a function of hydrogen dilution during deposition of a-Si:H thin films was examined. Finally, we present a first positron Doppler Broadening of Annihilation Radiation (DBAR) study of the emerging class of highly efficient thin film solar cells based on perovskites.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 1
DOI: 10.1088/1742-6596/791/1/012021
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“Strained graphene Hall bar”. Milovanovic SP, Peeters FM, Journal of physics : condensed matter 29, 075601 (2017). http://doi.org/10.1088/1361-648X/AA50D3
Abstract: The effects of strain, induced by a Gaussian bump, on the magnetic field dependent transport properties of a graphene Hall bar are investigated. The numerical simulations are performed using both classical and quantum mechanical transport theory and we found that both approaches exhibit similar characteristic features. The effects of the Gaussian bump are manifested by a decrease of the bend resistance, RB, around zero-magnetic field and the occurrence of side-peaks in RB. These features are explained as a consequence of bump-assisted scattering of electrons towards different terminals of the Hall bar. Using these features we are able to give an estimate of the size of the bump. Additional oscillations in RB are found in the quantum description that are due to the population/depopulation of Landau levels. The bump has a minor influence on the Hall resistance even for very high values of the pseudo-magnetic field. When the bump is placed outside the center of the Hall bar valley polarized electrons can be collected in the leads.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 12
DOI: 10.1088/1361-648X/AA50D3
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“Aharonov-Bohm oscillations in phosphorene quantum rings”. Li LL, Moldovan D, Vasilopoulos P, Peeters FM, Physical review B 95, 205426 (2017). http://doi.org/10.1103/PHYSREVB.95.205426
Abstract: The Aharonov-Bohm (AB) effect in square phosphorene quantum rings, with armchair and zigzag edges, is investigated using the tight-binding method. The energy spectra and wave functions of such rings, obtained as a function of the magnetic flux Phi threading the ring, are strongly influenced by the ringwidthW, an in-plane electric field E-p, and a side-gating potential V-g. Compared to a square dot, the ring shows an enhanced confinement due to its inner edges and an interedge coupling along the zigzag direction, both of which strongly affect the energy spectrum and the wave functions. The energy spectrum that is gapped consists of a regular part, of conduction (valence) band states, that shows the usual AB oscillations in the higher-(lower-) energy region, and of edge states, in the gap, that exhibit no AB oscillations. As the width W decreases, the AB oscillations become more distinct and regular and their period is close to Phi(0)/2, where the flux quantum Phi(0) = h/e is the period of an ideal circular ring (W -> 0). Both the electric field E-p and the side-gating potential V-g reduce the amplitude of the AB oscillations. The amplitude can be effectively tuned by E-p or V-g and exhibits an anisotropic behavior for different field directions or side-gating configurations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 16
DOI: 10.1103/PHYSREVB.95.205426
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“Effects of spatially engineered Dzyaloshinskii-Moriya interaction in ferromagnetic films”. Mulkers J, Van Waeyenberge B, Milošević, MV, Physical review B 95, 144401 (2017). http://doi.org/10.1103/PhysRevB.95.144401
Abstract: The Dzyaloshinskii-Moriya interaction (DMI) is a chiral interaction that favors formation of domain walls. Recent experiments and ab initio calculations show that there are multiple ways to modify the strength of the interfacially induced DMI in thin ferromagnetic films with perpendicular magnetic anisotropy. In this paper we reveal theoretically the effects of spatially varied DMI on the magnetic state in thin films. In such heterochiral 2D structures we report several emergent phenomena, ranging from the equilibrium spin canting at the interface between regions with different DMI, over particularly strong confinement of domain walls and skyrmions within high-DMI tracks, to advanced applications such as domain tailoring nearly at will, design of magnonic waveguides, and much improved skyrmion racetrack memory.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 60
DOI: 10.1103/PhysRevB.95.144401
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“Exciton states in a circular graphene quantum dot: Magnetic field induced intravalley to intervalley transition”. Li LL, Zarenia M, Xu W, Dong HM, Peeters FM, Physical review B 95, 045409 (2017). http://doi.org/10.1103/PHYSREVB.95.045409
Abstract: The magnetic-field dependence of the energy spectrum, wave function, binding energy, and oscillator strength of exciton states confined in a circular graphene quantum dot (CGQD) is obtained within the configuration interaction method. We predict that (i) excitonic effects are very significant in the CGQD as a consequence of a combination of geometric confinement, magnetic confinement, and reduced screening; (ii) two types of excitons (intravalley and intervalley) are present in the CGQD because of the valley degree of freedom in graphene; (iii) the intravalley and intervalley exciton states display different magnetic-field dependencies due to the different electron-hole symmetries of the single-particle energy spectra; (iv) with increasing magnetic field, the exciton ground state in the CGQD undergoes an intravalley to intervalley transition accompanied by a change of angular momentum; (v) the exciton binding energy does not increase monotonically with the magnetic field due to the competition between geometric and magnetic confinements; and (vi) the optical transitions of the intervalley and intravalley excitons can be tuned by the magnetic field, and valley-dependent excitonic transitions can be realized in a CGQD.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 14
DOI: 10.1103/PHYSREVB.95.045409
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“Reversible structural transition in nanoconfined ice”. Satarifard V, Mousaei M, Hadadi F, Dix J, Sobrino Fernández M, Carbone P, Beheshtian J, Peeters FM, Neek-Amal M, Physical review B 95, 064105 (2017). http://doi.org/10.1103/PHYSREVB.95.064105
Abstract: The report on square ice sandwiched between two graphene layers by Algara-Siller et al. [Nature (London) 519, 443 (2015)] has generated a large interest in this system. By applying high lateral pressure on nanoconfined water, we found that monolayer ice is transformed to bilayer ice when the two graphene layers are separated by H = 6,7 angstrom. It was also found that three layers of a denser phase of ice with smaller lattice constant are formed if we start from bilayer ice and apply a lateral pressure of about 0.7 GPa with H = 8,9 angstrom. The lattice constant (2.5-2.6 angstrom) in both transitions is found to be smaller than those typical for the known phases of ice and water, i.e., 2.8 angstrom. We validate these results using ab initio calculations and find good agreement between ab initio O-O distance and those obtained from classical molecular dynamics simulations. The reversibility of the mentioned transitions is confirmed by decompressing the systems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 23
DOI: 10.1103/PHYSREVB.95.064105
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“Electronic and transport properties of n-type monolayer black phosphorus at low temperatures”. Han FW, Xu W, Li LL, Zhang C, Dong HM, Peeters FM, Physical review B 95, 115436 (2017). http://doi.org/10.1103/PhysRevB.95.115436
Abstract: We present a detailed theoretical study of the electronic and transport properties of monolayer black phosphorus (BP). This study is motivated by recent experimental activities in investigating n-type few-layer BP systems. The electron density of states, the screening length, and the low-temperature electron mobility are calculated for monolayer BP (MLBP). In particular, the electron transport mobilities along the armchair and zigzag directions are examined on the basis of the momentum-balance equation derived from a semiclassical Boltzmann equation. The anisotropic electron mobilities in MLBP along different directions are demonstrated where the electron-impurity scattering is considered. Furthermore, we compare the results obtained from two electronic band structures of MLBP and find that the simplified model can describe quite rightly the electronic and transport properties of MLBP. This study is relevant to the application of few-layer BP based electronic systems as advanced electronic devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 12
DOI: 10.1103/PhysRevB.95.115436
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“Ab initio study of hydrogenic effective mass impurities in Si nanowires”. Peelaers H, Durgun E, Partoens B, Bilc DI, Ghosez P, Van de Walle CG, Peeters FM, Journal of physics : condensed matter 29, 095303 (2017). http://doi.org/10.1088/1361-648X/AA5768
Abstract: The effect of B and P dopants on the band structure of Si nanowires is studied using electronic structure calculations based on density functional theory. At low concentrations a dispersionless band is formed, clearly distinguishable from the valence and conduction bands. Although this band is evidently induced by the dopant impurity, it turns out to have purely Si character. These results can be rigorously analyzed in the framework of effective mass theory. In the process we resolve some common misconceptions about the physics of hydrogenic shallow impurities, which can be more clearly elucidated in the case of nanowires than would be possible for bulk Si. We also show the importance of correctly describing the effect of dielectric confinement, which is not included in traditional electronic structure calculations, by comparing the obtained results with those of G(0)W(0) calculations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 1
DOI: 10.1088/1361-648X/AA5768
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“Band alignment of lateral two-dimensional heterostructures with a transverse dipole”. Leenaerts O, Vercauteren S, Partoens B, Applied physics letters 110, 181602 (2017). http://doi.org/10.1063/1.4982791
Abstract: It was recently shown that the electronic band alignment in lateral two-dimensional heterostructures is strongly dependent on the system geometry, such as heterostructure width and layer thickness. This is so even in the absence of polar edge terminations because of the appearance of an interface dipole between the two different materials. In this study, this work is expanded to include two-dimensional materials that possess an electronic dipole over their surface, i.e., in the direction transverse to the crystal plane. To this end, a heterostucture consisting of polar hydrofluorinated graphene and non-polar graphane layers is studied with first-principles calculations. As for nonpolar heterostructures, a significant geometry dependence is observed with two different limits for the band offset. For infinitely wide heterostructures, the potential step in the vacuum is equally divided over the two sides of the heterostructure, resulting in a finite potential step in the heterostructure. For infinitely thick heterostructure slabs, on the other hand, the band offset is reduced, similar to the three-dimensional case.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 4
DOI: 10.1063/1.4982791
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