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The dielectric response (permittivity and losses) of epitaxial CoFe2O4–BaTiO3 thin film nanocomposites deposited under different conditions has been measured. Exhaustive microstructural analyses have allowed tracking the evolution of structure and morphology as a function of thickness, deposition temperature and rate. It is found that the dielectric permittivity of the nanocomposite increases with the grain size of the BaTiO3 matrix and when reducing its unit cell volume, while losses are quite insensitive to changes in morphology and crystal structure of the ferroelectric phase. We analyze the consequences of these results in view of the functional optimization of nanocomposites. [ABSTRACT FROM AUTHOR]

The dielectric response of epitaxial Co[Fe.sub.2][O.sub.4]-BaTi[O.sub.3] thin film nanocomposites deposited under different conditions is measured. The studies have shown that the dielectric permittivity of the nanocomposite has increased with the grain size of the BaTi[O.sub.3] matrix and when reducing its unit cell volume, while losses are quite insensitive to changes in morphology and crystal structure of the ferroelectric phase.

Material selective sensitive of a magneto-optical polar Kerr effect to magnetic contributions from different inclusions in self-organized nanostructures is described. Magneto-optic selective sensitivity is explained as an effect of different complex diagonal and off-diagonal permittivity tensor elements of two materials.

The growth of self-assembled (0.65)BiFe[O.sub.3]-(0.35)Co[Fe.sub.2][O.sub.4] (BFO-CFO) nanostructures on SrTi[O.sub.3] (STO) substrates with different orientations and the effect of growth temperature on the crystal phases and their strain are studied. The studies have shown that interfacial stress has dominated the elastic properties of CFO crystallites and might play a fundamental on the interface magnetoelectric coupling in these nanocomposites.

A report on the magneto-optical measurements of an epitaxial SrRuO3 film grown on SrTiO3 (0 0 1), which previously was determined to be single domain oriented by x-ray diffraction and Raman spectroscopy techniques, is presented. The experiments performed reveal a large Kerr rotation that reaches a maximum value of about 0.5 degrees at low temperature.

Material selective sensitivity of a magneto-optical polar Kerr effect to magnetic contributions from different inclusions in self-organized magnetic nanostructures is presented. The method is supported by modeling of the magneto-optic response based on the effective medium approximation and by hysteresis loop measurement of the multiferroic BiFeO3–CoFe2O4 self-assembled nanostructure. Magneto-optic selective sensitivity is demonstrated and explained as an effect of different complex diagonal and off-diagonal permittivity tensor elements of two materials. [ABSTRACT FROM AUTHOR]

Self-assembled (0.65)BiFeO3–(0.35)CoFe2O4 (BFO-CFO) nanostructures were deposited on SrTiO3 (001) and (111) substrates by pulsed laser deposition at various temperatures from 500 to 800 °C. The crystal phases and the lattice strain for the two different substrate orientations have been determined and compared. The films grow epitaxial on both substrates but separation of the spinel and perovskite crystallites, without parasitic phases, is only obtained for growth temperatures of around 600–650 °C. The BFO crystallites are out-of-plane expanded on STO(001), whereas they are almost relaxed on (111). In contrast, CFO crystallites grow out-of-plane compressed on both substrates. The asymmetric behavior of the cell parameters of CFO and BFO is discussed on the basis of the role of the epitaxial stress caused by the substrate and the spinel-perovskite interfacial stress. It is concluded that interfacial stress dominates the elastic properties of CFO crystallites and thus it may play a fundamental on the interface magnetoelectric coupling in these nanocomposites. [ABSTRACT FROM AUTHOR]

We report on the magneto-optical measurements of an epitaxial SrRuO3 film grown on SrTiO3 (0 0 1), which previously was determined to be single domain orientated by x-ray diffraction and Raman spectroscopy techniques. Our experiments reveal a large Kerr rotation, which reaches a maximum value of about 0.5° at low temperature. By measuring magnetic hysteresis loops at different temperatures, we determined the temperature dependence of the Kerr rotation in the polar configuration. Values of the anisotropic magnetoresistance ∼20% have been measured. These values are remarkably higher than those of other metallic oxides such as manganites. This striking difference can be attributed to the strong spin-orbit interaction of the Ru 4d ion in the SrRuO3 compound. [ABSTRACT FROM AUTHOR]

LaNiO3 (LNO) thin films of 14 nm and 35 nm thicknesses grown epitaxially on LaAlO3 (LAO) and (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) substrates are studied using High Resolution Transmission Electron Microscopy (HRTEM) and High Angle Annular Dark Field (HAADF) imaging. The strain state of the films is studied using Geometric Phase Analysis (GPA). Results show the successful in-plane adaptation of the films to the substrates, both in the compressive (LAO) and tensile (LSAT) cases. Through the systematic analysis of HRTEM superstructure contrast modulation along different crystal orientations, localized regions of the monoclinic LaNiO2.5 phase are detected in the 35 nm films. [ABSTRACT FROM AUTHOR]

We show that yttria-stabilized zirconia (YSZ) films deposited on structurally dissimilar SrTiO3(110) substrates exhibit two-dimensional layer-by-layer growth. We observed that, up to a thickness of about 15 nm, the square (001) basal plane of the cubic YSZ grows epitaxially on the rectangular (110) crystallographic plane of SrTiO3 substrates, with [110]YSZ(001)// [001]SrTiO3(110) epitaxial relationship. Thus, the heterointerface presents symmetry discontinuity between the YSZ(001) film and the lower surface symmetry SrTiO3(110) substrate. Beyond this specific case, we envisage similar approaches to develop other innovative oxide interfaces showing similar crystal symmetry discontinuities. [ABSTRACT FROM AUTHOR]

Engineering interfaces in perovskite/spinel heterostructures is challenged by structural differences. We have used kinetic growth limitations to fabricate flat BaTiO3/CoFe2O4 (BTO/CFO) epitaxial bilayers on La2/3Sr1/3MnO3/SrTiO3(001). In situ analysis of lattice strain during growth has revealed that BTO grows relaxed on highly lattice-mismatched CFO, thus suppressing tensile epitaxial stress effects. As a result, BTO is ferroelectric along the out-of-plane direction with bulk-like polarization. These results show that very high lattice mismatch in heteroepitaxy can be an opportunity rather than a limitation to integrate dissimilar materials with optimized functional properties. [ABSTRACT FROM AUTHOR]

Ferroelectric BaTiO3 is rarely used in monolithic Si devices due to the low quality of BaTiO3 films on Si, as polycrystallinity, degradation of bottom Pt electrodes, low polarization, and high roughness. Here, we overcome these limitations by using a buffer structure that combines yttria-stabilized zirconia, CeO2, and conducting LaNiO3. BaTiO3 films on the multilayered buffer, with total thickness of the buffer below 100 nm, are epitaxial, display remnant polarization of 6-10 μC/cm2, and have roughness of a few Å. These unprecedented properties pave the way to integrate ferroelectric BaTiO3 into Si platforms. [ABSTRACT FROM AUTHOR]

Quasi-tetragonal BiFeO3 (T-BFO) multiferroic oxide is receiving much attention due to prospects of enhanced ferroelectric polarization and close-to-room-temperature phase transitions. Here, we report on the role of deposition temperature on the stabilization of the T-BFO phase on LaAlO3(001) substrates. T-BFO has only been obtained in a narrow temperature window. We will show that competitive formation of rhombohedral BFO and thermal decomposition at lower and higher temperatures, respectively, bounds the stability range of T-BFO. However, we show that addition of a secondary spinel phase, creating vertical interfaces, extends the formation range of T-BFO. [ABSTRACT FROM AUTHOR]

Self-assembled La0.7Sr0.3MnO3 perovskite nanodots have been grown on highly mismatched rock-salt type MgO substrates by chemical solution deposition. The interfacial dislocation structure indicates that the relaxation mechanism is governed by the easy glide of MgO 1/2<101>{101} dislocations towards the interface, where they dissociate into misfit-relieving and tilting components. The latter induce a 4-domain tilt pattern superimposed to the main cube-on-cube epitaxial orientation. It is shown that the inheritance of the rotational component of the Burgers vector has detrimental consequences on the interfacial quality, evidencing the impact of structural and plastic dissimilarity on the design of self-assembled nanostructures. [ABSTRACT FROM AUTHOR]

Abstract: We report on the dielectric characterization of CoFe2O4–BaTiO3 nanocomposites grown by rf sputtering. Dielectric properties have been analyzed for samples grown at different deposition temperatures and with different thicknesses. Impedance spectroscopy data has been analyzed by fitting to an equivalent circuit and different contributions have been identified. Correlations between dielectric properties and deposition temperature and thickness have been established. [Copyright &y& Elsevier]

Abstract: BiFeO3–CoFe2O4 epitaxial nanocomposites have been deposited on SrTiO3 (001) substrates by pulsed laser deposition. We present here a study of the influence of the deposition temperature (T S), in the 550–800°C range, on the film composition, morphology and microstructure. Electron-probe microanalysis shows strong reduction of the Bi content in the films when increasing T S. Films prepared at T S=750°C and above are virtually Bi-free. X-ray diffraction (XRD) data show that, due to the volatility of Bi, there is a progressive reduction in the amount of BiFeO3. The deposition temperature and the concomitant presence of Fe x O y spurious phases in the nanocomposites grown at high temperature promote radical changes in film morphology and magnetization. It thus follows that a temperature range suitable for controlled modification of nanocomposites morphology would be extremely narrow. [Copyright &y& Elsevier]

Abstract: We report on the sputtering growth and characterization of nanostructures formed by a ferrimagnetic spinel (CoFe2O4) and a ferroelectric perovskite (BaTiO3) on (001) and (111) oriented SrTiO3 substrates. We present analysis of the crystal structure (crystal phases and lattice strain) and the surface morphology by X-ray diffractometry and by atomic force microscopy, respectively. Films grown on both substrates display phase segregation, being textured (either (001) or (111)) the films deposited at 700°C and polycrystalline the ones grown at the highest deposition temperature (800°C). The magnetic easy axis of films grown on SrTiO3(001) is out-of-plane. It is found that phase separation and island size are depending on the growth conditions and the role of adatom supersaturation during growth is discussed. [Copyright &y& Elsevier]

We report a Raman scattering investigation of columnar BiFeO3-CoFe2O4 (BFO-CFO) epitaxial thin film nanostructures, where BFO pillars are embedded in a CFO matrix. The feasibility of a strain analysis is illustrated through an investigation of two nanostructures with different BFO-CFO ratios. We show that the CFO matrix presents the same strain state in both nanostructures, while the strain state of the BFO pillars depends on the BFO/CFO ratio with an increasing tensile strain along the out-of-plane direction with decreasing BFO content. Our results demonstrate that Raman scattering allows monitoring strain states in complex 3D multiferroic pillar/matrix composites. [ABSTRACT FROM AUTHOR]

Abstract: We report on the magnetoelectric characterization of epitaxial CoFe2O4–BaTiO3 nanocomposites grown by rf sputtering on Nb-doped SrTiO3 (001). Multiferroicity of the material is corroborated with both, ferroelectric and ferromagnetic hysteresis loops. Magnetoelectric coupling is investigated via magnetocapacitance measurements; a change of the capacitance of about 2% is observed for an applied magnetic field of 8T. The possible origins of this magnetocapacitance are discussed. [Copyright &y& Elsevier]

We have investigated the thermal stability of platinum electrodes on oxide substrates for oxide-based devices. We show that flat epitaxial Pt(111) bottom electrodes, deposited on SrTiO3(111) and Al2O3(0001) substrates, can be stable against dewetting up to usual oxide-deposition temperatures (Ts) by increasing Pt film thickness (tPt) and preferably using SrTiO3(111) rather than Al2O3(0001) substrates. Subsequently, high-quality epitaxial biferroic YMnO3/Pt/oxide-substrate heterostructures have been grown. A diagram of morphological and crystalline quality versus tPt and Ts is given for both YMnO3/Pt/SrTiO3(111) and YMnO3/Pt/Al2O3(0001) heterostructures. These results shall guideline the growth of other functional oxide thin films on Pt electrodes. [ABSTRACT FROM AUTHOR]

In magnetoelectrically coupled CoFe2O4–BiFeO3 nanostructures vertical and lateral lattice parameters of both phases are determined. We find that the in-plane lattice parameter of CoFe2O4 is fully relaxed whereas it presents compressive strain along the out-of-plane direction. Although the CoFe2O4–BiFeO3 interface is semicoherent, CoFe2O4 out-of-plane lattice strain is not relaxed after selective removal of the matrix and thus it is of nonelastic origin. In spite of the absence of elastic residual strain caused by CoFe2O4–BiFeO3 interfaces, the two phases are mechanically coupled as demonstrated by the electrical switching of the magnetization. [ABSTRACT FROM AUTHOR]

Ferromagnetic SrRuO3 films with controlled in-plane magnetic anisotropy have been deposited on nominally exact (miscut <0.1°) SrTiO3(001) substrates. Films grown on as-received substrates display in-plane uniaxial magnetic anisotropy whereas films grown on treated TiO2-terminated surfaces are magnetically biaxial. It is found that the in-plane magnetic anisotropy is intimately linked to the in-plane crystallographic texture: whereas the former films are single domain, the latter are twinned. The authors show that the different textures are determined by the growth mechanisms, step flow or layer by layer, which in turn are critically determined by the substrate surface conditions. [ABSTRACT FROM AUTHOR]

A response by R. Muralidharan and colleagues to a letter to the editor about their article on residual lattice strain in epitaxial multiferroic nanostructures, in a previous issue is presented.

Ultrathin Pt films grown on insulating ferrimagnetic CoFe2O4 (111) epitaxial films display a magnetoresistance upon rotating the magnetization of the magnetic layer. We report here x-ray magnetic circular dichroism (XMCD) recorded at Pt-L2,3 and Pt-M3 edges. The results indicate that the Pt magnetic moment, if any, is below the detection limit (<0.001µB/Pt), thus strongly favoring the view that the presence of CoFe2O4 does not induce the formation of magnetic moments in Pt. Therefore, the observed magnetoresistance cannot be attributed to some sort of proximity-induced magnetic moments at Pt ions and subsequent magnetic-field dependent scattering. It thus follows that either bulk (spin Hall and inverse spin Hall effects) or interface (Rashba) spin-orbit related effects dominate the observed magnetoresistance. Furthermore, comparison of bulk magnetization and XMCD data at (Fe,Co)-L2,3 edges suggests the presence of some spin disorder in the CoFe2O4 layer which may be relevant for the observed anomalous nonsaturating field dependence of spin Hall magnetoresistance. [ABSTRACT FROM AUTHOR]

Strain effects on epitaxial thin films of LaNiO3 grown on different single crystalline substrates are studied by Raman scattering and first-principles simulation. New Raman modes, not present in bulk or fully relaxed films, appear under both compressive and tensile strains, indicating symmetry reductions. Interestingly, the Raman spectra and the underlying crystal symmetry for tensile and compressively strained films are different. Extensive mapping of LaNiO3 phase stability is addressed by simulations, showing that a variety of crystalline phases are indeed stabilized under strain. The calculated Raman frequencies reproduce the principal features of the experimental spectra, supporting the validity of the multiple strain-driven structural transitions predicted by the simulations. [ABSTRACT FROM AUTHOR]

Recent findings show the emergence of two-dimensional electron gases (2DEGs) at LaAlO3/SrTiO3 interfaces along different orientations; yet details on band reconstructions have remained so far unknown. Via x-ray linear dichroism spectroscopy, we demonstrate that crystal symmetry imposes distinctive 2DEG orbital hierarchies on (001)-and (110)-oriented quantum wells, allowing selective occupancy of states of different symmetry. Such orientational tuning expands the possibilities for electronic engineering of 2DEGs and opens up enticing opportunities to understand the link between orbital symmetry and complex correlated states at LaAlO3/SrTiO3 quantum wells. [ABSTRACT FROM AUTHOR]

Understanding the electronic properties resulting from soft-hard material interfacial contact has elevated the utility of functional polymers in advanced materials and nanoscale structures, such as in work function engineering of two-dimensional (2D) materials to produce new types of high-performance devices. In this paper, we describe the electronic impact of functional polymers, containing both zwitterionic and fluorocarbon components in their side chains, on the work function of monolayer graphene through the preparation of negative-tone photoresists, which we term "fluorozwitterists." The zwitterionic and fluorinated groups each represent dipole-containing moieties capable of producing distinct surface energies as thin films. Kelvin probe force microscopy revealed these polymers to have a p -doping effect on graphene, which contrasts the work function decrease typically associated with polymer-to-graphene contact. Copolymerization of fluorinated zwitterionic monomers with methyl methacrylate and a benzophenone-substituted methacrylate produced copolymers that were amenable to photolithographic fabrication of fluorozwitterist structures. Consequently, spatial alteration of zwitterion coverage across graphene yielded stripes that resemble a lateral p - i - n diode configuration, with local increase or decrease of work function. Overall, this polymeric fluorozwitterist design is suitable for enabling simple, solution-based surface patterning and is anticipated to be useful for spatial work function modulation of 2D materials integrated into electronic devices., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

FeRh shows an antiferromagnetic to ferromagnetic phase transition above room temperature, which permits its use as an antiferromagnetic memory element. However, its antiferromagnetic order is sensitive to small variations in crystallinity and composition, challenging its integration into flexible devices. Here, we show that flexible FeRh films of high crystalline quality can be synthesized by using mica as a substrate, followed by a mechanical exfoliation of the mica. The magnetic and transport data indicate that the FeRh films display a sharp antiferromagnetic to ferromagnetic phase transition. Magnetotransport data allow for the observation of two distinguishable resistance states, which are written after a field-cooling procedure. It is shown that the memory states are robust under the application of magnetic fields of up to 10 kOe., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The metastable orthorhombic phase of Hf 0.5 Zr 0.5 O 2 (HZO) can be stabilized in thin films on La 0.67 Sr 0.33 MnO 3 (LSMO) buffered (001)-oriented SrTiO 3 (STO) by intriguing epitaxy that results in (111)-HZO oriented growth and robust ferroelectric properties. Here, we show that the orthorhombic phase can also be epitaxially stabilized on LSMO/STO(110), presenting the same out-of-plane (111) orientation but a different distribution of the in-plane crystalline domains. The remanent polarization of HZO films with a thickness of less than 7 nm on LSMO/STO(110) is 33 μC cm -3 , which corresponds to a 50% improvement over equivalent films on LSMO/STO(001). Furthermore, HZO on LSMO/STO(110) presents higher endurance, switchable polarization is still observed up to 4 × 10 10 cycles, and retention of more than 10 years. These results demonstrate that tuning the epitaxial growth of ferroelectric HfO 2 , here using STO(110) substrates, allows the improvement of functional properties of relevance for memory applications.

Formed at the confluence of marine and fresh waters, estuaries experience both the seaside pressures of rising sea levels and increasing storm severity, and watershed and precipitation changes that are shifting the quality and quantity of freshwater and sediments delivered from upstream sources. Boating, shoreline hardening, harvesting pressure, and other signatures of human activity are also increasing as populations swell in coastal regions. Given this shifting landscape of pressures, the factors most threatening to estuary health and stability are often uncertain. To identify the greatest contemporary threats to coastal wetlands and oyster reefs across the southeastern United States (Mississippi to North Carolina), we summarized recent population growth and land-cover change and surveyed estuarine management and science experts. From 1996 to 2019, human population growth in the region varied from a 17% decrease to a 171% increase (mean = +43%) with only 5 of the 72 SE US counties losing population, and nearly half growing by more than 40%. Individual counties experienced between 999 and 19,253 km 2 of new development (mean: 5725 km 2 ), with 1-5% (mean: 2.6%) of undeveloped lands undergoing development over this period across the region. Correspondingly, our survey of 169 coastal experts highlighted development, shoreline hardening, and upstream modifications to freshwater flow as the most important local threats facing coastal wetlands. Similarly, experts identified development, upstream modifications to freshwater flow, and overharvesting as the most important local threats to oyster reefs. With regards to global threats, experts categorized sea level rise as the most pressing to wetlands, and acidification and precipitation changes as the most pressing to oyster reefs. Survey respondents further identified that more research, driven by collaboration among scientists, engineers, industry professionals, and managers, is needed to assess how precipitation changes, shoreline hardening, and sea level rise are affecting coastal ecosystem stability and function. Due to the profound role of humans in shaping estuarine health, this work highlights that engaging property owners, recreators, and municipalities to implement strategies to improve estuarine health will be vital for sustaining coastal systems in the face of global change., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Shrubs are invading into grasslands around the world, but we don't yet know how these shrubs will fare in a warmer future. In ecotonal coastal wetland ecosystems, woody mangroves are encroaching into herbaceous salt marshes owing to changes in temperature, precipitation, and sediment dynamics. Increasing mangrove biomass in wetlands often increases carbon storage, which is high in these productive ecosystems, but little is known about how mangrove growth will change in response to warming. To address this knowledge gap, we deployed warming experiments at three coastal wetland sites along a latitudinal gradient in northeast Florida where Avicennia germinans, black mangroves, are encroaching into salt marshes. We achieved air temperature warming (+1.6°C during the day) at all three sites and measured stem elongation, canopy height and area changes, and leaf and node number. After 2 yr of warming, we found that mangrove growth rate in height increased due to warming. Warming increased stem elongation by 130% over unwarmed control plots after 1 yr at the northern site. Mangrove growth in canopy area did not respond to warming. Site differences in growth rate were pronounced, and mangrove growth in both height and area were lowest at the northern site, despite greater impacts of warming at that site. We also found that area-based relative growth rate was five times higher across all treatments than height-based relative growth rate, indicating that mangroves are growing wider rather than taller in these ecotonal environments. Our findings indicate that the growth effect of experimental warming depends on site characteristics and growth parameter measured. We also propose that differential mangrove growth across the three sites may be driven by biotic factors such as the identity of the salt marsh species into which mangroves are encroaching. Our results suggest that, as seen in other ecosystems, wetland plants may respond most strongly to warming at their poleward range edge., (© 2021 by the Ecological Society of America.)

The antiferromagnetic to ferromagnetic transition occurring above room temperature in FeRh is attracting interest for applications in spintronics, with perspectives for robust and untraceable data storage. Here, we show that FeRh films can be grown on a flexible metallic substrate (tape shaped), coated with a textured rock-salt MgO layer, suitable for large-scale applications. The FeRh tape displays a sharp antiferromagnetic to ferromagnetic transition at about 90 °C. Its magnetic properties are preserved by bending (radii of 300 mm), and their anisotropic magnetoresistance (up to 0.05%) is used to illustrate data writing/reading capability.

The generality of ecological patterns depends inextricably on the scale at which they are examined. We investigated patterns of crab distribution and the relationship between crabs and vegetation in salt marshes at multiple scales. By using consistent monitoring protocols across 15 U.S. National Estuarine Research Reserves, we were able to synthesize patterns from the scale of quadrats to the entire marsh landscape to regional and national scales. Some generalities emerged across marshes from our overall models, and these are useful for informing broad coastal management policy. We found that crab burrow distribution within a marsh could be predicted by marsh elevation, distance to creek and soil compressibility. While these physical factors also affected marsh vegetation cover, we did not find a strong or consistent overall effect of crabs at a broad scale in our multivariate model, though regressions conducted separately for each site revealed that crab burrows were negatively correlated with vegetation cover at 4 out of 15 sites. This contrasts with recent smaller-scale studies and meta-analyses synthesizing such studies that detected strong negative effects of crabs on marshes, likely because we sampled across the entire marsh landscape, while targeted studies are typically limited to low-lying areas near creeks, where crab burrow densities are highest. Our results suggest that sea-level rise generally poses a bigger threat to marshes than crabs, but there will likely be interactions between these physical and biological factors. Beyond these generalities across marshes, we detected some regional differences in crab community composition, richness, and abundance. However, we found striking differences among sites within regions, and within sites, in terms of crab abundance and relationships to marsh integrity. Although generalities are broadly useful, our findings indicate that local managers cannot rely on data from other nearby systems, but rather need local information for developing salt marsh management strategies., (© 2019 by the Ecological Society of America.)

Conventional strain engineering of epitaxial ferroelectric oxide thin films is based on the selection of substrates with a suitable lattice parameter. Here, we show that the variation of oxygen pressure during pulsed laser deposition is a flexible strain engineering method for epitaxial ferroelectric BaTiO 3 films either on perovskite substrates or on Si(001) wafers. This unconventional growth strategy permits continuous tuning of strain up to high levels (ε > 0.8%) in films greater than one hundred nanometers thick, as well as selecting the polar axis orientation to be either parallel or perpendicular to the substrate surface plane.

Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from the synthesis to mapped tidal wetlands, applying models fit using empirical data and applied using soil, vegetation and salinity maps, and relying on independently generated soil carbon maps. Soil carbon stocks were far lower on average and varied less spatially and with depth than stocks calculated from available soils maps. Further, variation in carbon density was not well-predicted based on climate, salinity, vegetation, or soil classes. Instead, the assembled dataset showed that carbon density across the conterminous united states (CONUS) was normally distributed, with a predictable range of observations. We identified the simplest strategy, applying mean carbon density (27.0 kg C m -3 ), as the best performing strategy, and conservatively estimated that the top meter of CONUS tidal wetland soil contains 0.72 petagrams C. This strategy could provide standardization in CONUS tidal carbon accounting until such a time as modeling and mapping advancements can quantitatively improve accuracy and precision.