Thermally activated processes for ferromagnet intercalation in graphene-heavy metal interfaces

The development of graphene (Gr) spintronics requires the ability to engineer epitaxial Gr heterostructures with interfaces of high quality, in which the intrinsic properties of Gr are modified through proximity with a ferromagnet to allow for efficient room temperature spin manipulation or the stabilization of new magnetic textures. These heterostructures can be prepared in a controlled way by intercalation through graphene of different metals. Using photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM), we achieve a nanoscale control of thermally activated intercalation of a homogeneous ferromagnetic (FM) layer underneath epitaxial Gr grown onto (111)-oriented heavy metal (HM) buffers deposited, in turn, onto insulating oxide surfaces. XPS and STM demonstrate that Co atoms evaporated on top of Gr arrange in 3D clusters and, upon thermal annealing, penetrate through and diffuse below Gr in a 2D fashion. The complete intercalation of the metal occurs at specific temperatures, depending on the type of metallic buffer. The activation energy and the optimum temperature for the intercalation processes are determined. We describe a reliable method to fabricate and characterize in situ high-quality Gr-FM/HM heterostructures, enabling the realization of novel spin-orbitronic devices that exploit the extraordinary properties of GrThis research was supported by the Regional Government of Madrid through projects P2018/NMT-4321 (NANOMAGCOST-CM) and P2018/NMT-4511 (NMAT2D) and by the Spanish Ministry of Economy and Competitiveness (MINECO) through projects RTI2018-097895-B-C42, FIS2016-78591-C3-1-R, PGC2018-098613-B-C21, PGC2018-093291-B-I00, FIS2015-67367-C2-1-P, and PCIN-2015-111 (FLAGERA JTC2015 Graphene Flagship “SOgraph”). IFIMAC acknowledges support from the ″Maria de Maeztu″ programme for units of Excellence in R&D (MDM-2014-0377). IMDEA Nanoscience is supported by the “Severo Ochoa” programme for the Centres of Excellence in R&D, MINECO (grant number SEV-2016-0686

Variable style of transition between Palaeogene fluvial fan and lacustrine systems, southern Pyrenean foreland, NE Spain

Two Palaeogene fluvial fan systems linked to the south-Pyrenean margin are recognized in the eastern Ebro Basin: the Cardona–Su´ ria and Solsona–Sanau¨ ja fans. These had radii of 40 and 35 km and were 800 and 600 km2 in area respectively. During the Priabonian to the Middle Rupelian, the fluvial fans built into a hydrologically closed foreland basin, and shallow lacustrine systems persisted in the basin centre. In the studied area, both fans are part of the same upward-coarsening megasequence (up to 800 m thick), driven by hinterland drainage expansion and foreland propagation of Pyrenean thrusts. Fourteen sedimentary facies have been grouped into seven facies associations corresponding to medial fluvial fan, channelized terminal lobe, nonchannelized terminal lobe, mudflat, deltaic, evaporitic playa-lake and carbonate-rich, shallow lacustrine environments. Lateral correlations define two styles of alluvial-lacustrine transition. During low lake-level stages, terminal lobes developed, whereas during lake highstands, fluvial-dominated deltas and interdistributary bays were formed. Terminal lobe deposits are characterized by extensive (100–600 m wide) sheet-like fine sandstone beds formed by sub-aqueous, quasi-steady, hyperpycnal turbidity currents. Sedimentary structures and trace fossils indicate rapid desiccation and subaerial exposure of the lobe deposits. These deposits are arranged in coarsening–fining sequences (metres to tens of metres in thickness) controlled by a combination of tectonics, climatic oscillations and autocyclic sedimentary processes. The presence of anomalously deeply incised distributary channels associated with distal terminal lobe or mudflat deposits indicates rapid lake-level falls. Deltaic deposits form progradational coarsening-upward sequences (several metres thick) characterized by channel and friction-dominated mouth-bar facies overlying white-grey offshore lacustrine facies. Deltaic bar deposits are less extensive (50–300 m wide) than the terminal lobes and were also deposited by hyperpycnal currents, although they lack evidence of emergence. Sandy deltaic deposits accumulated locally at the mouths of main feeder distal fan streams and were separated by muddy interdistributary bays; whereas the terminal lobe sheets expand from a series of mid-fan intersection points and coalesced to form a more continuous sandy fan fringe

Spin Seebeck effect in a weak ferromagnet

We report the observation of room temperature spin Seebeck effect (SSE) in a weak ferromagnetic normal spinel Zinc Ferrite (ZFO). Despite the weak ferromagnetic behavior, the measurements of the SSE in ZFO show a thermoelectric voltage response comparable with the reported values for other ferromagnetic materials. Our results suggest that SSE might possibly originate from the surface magnetization of the ZFO.This work was supported by Solid State Group (GES) at the University of Antioquia in the framework of Sustainability Strategy 2014–2015; Colombian Science, technology and innovation department (COLCIENCIAS, PhD student grant, conv. 567); Municipality of Medellin through SAPIENCIA agency (EnlazaMundos program, conv. 2014); J.D.A. is thankful to CODI-UdeA by financial backing. We also thank the Spanish Ministry of Science (through and MAT2011-27553-C02, including FEDER funding); the Aragón Regional Government (Project No. E26); and Thermo-Spintronic Marie Curie CIG (Grant Agreement No. 304043)-EU. Project No. PRI-PIBJP-2011-0794.Peer reviewe

Data for: Genetically-based trait coordination and phenotypic plasticity of growth, gas exchange, allometry and hydraulics across the distribution range of Pinus pinaster

Studying intraspecific trait variation across environments is key for understanding how resource-use strategies evolve. It is hypothesized that plants from mesic environments have evolved towards a more acquisitive strategy with high growth potential and phenotypic plasticity, while populations from xeric continental climates exhibit a conservative strategy with slower growth and better physiological performance under drier conditions. We tested this hypothesis through the phenotypical characterization of 14-year-old Pinus pinaster Aiton trees from twenty range-wide populations growing in two climatically contrasting common gardens. We measured twenty-one traits related to growth, leaf morphology, gas exchange, photochemistry, and hydraulics. Consistent with our hypothesis, we found that populations from mesic oceanic areas exhibited higher growth rates and higher allocation to leaf surface area under mesic conditions, along with greater plasticity in these traits. In contrast, xeric continental populations had better physiological status showing higher gas exchange rates and photochemical efficiency, but lower sapwood-specific hydraulic conductivity under drier conditions. Together, our results provide evidence that climate drives the joint evolution of leaf and stem traits and their plasticity following an acquisitive-conservative axis of resource use. Overall, trait coordination is found to be highly plastic likely to maximize plant performance under contrasting environmental conditions.Peer reviewe

Genetically based trait coordination and phenotypic plasticity of growth, gas exchange, allometry, and hydraulics across the distribution range of Pinus pinaster

Studying intraspecific trait variation across environments is key for understanding how resource-use strategies evolve. It is hypothesized that plants from mesic environments have evolved toward a more acquisitive strategy with high growth potential and phenotypic plasticity, while populations from xeric continental climates exhibit a conservative strategy with slower growth and better physiological performance under drier conditions.We tested this hypothesis through the phenotypical characterization of 14-yr-old Pinus pinaster Aiton trees from 20 range-wide populations growing in two climatically contrasting common gardens. We measured 20 traits related to growth, leaf morphology, gas exchange, photochemistry, and hydraulics.Consistent with our hypothesis, we found that populations from mesic oceanic areas exhibited higher growth rates and higher allocation to leaf surface area under mesic conditions, along with greater plasticity in these traits. By contrast, xeric continental populations had better physiological status, showing higher gas exchange rates and photochemical efficiency, but lower sapwood-specific hydraulic conductivity under drier conditions.Together, our results provide evidence that climate drives the joint evolution of leaf and stem traits and their plasticity following an acquisitive-conservative axis of resource use. Overall, trait coordination is found to be highly plastic, likely to maximize plant performance under contrasting environmental conditions