Suchergebnisse

AbstractThe catchment of the upper Clyde estuary has experienced a significant and steady increase of rainfall over the past twenty years. The corresponding increase of runoff has had a positive impact on the water quality both of the individual rivers and of the estuary. Examples are provided to show that approximately one third of some observed improvements are attributable to the additional dilution. It is emphasized that comparisons of water quality data, either by region or by period, should allow for climate variability.

6 pags., 5 figs. ; The interfacial Dzyaloshinskii-Moriya interaction (DMI) is of great interest as it can stabilize chiral spin structures in thin films. Experiments verifying the orientation of the interfacial DMI vector remain rare, in part due to the difficulty of separating vector components of DMI. In this study, Fe/Ni bilayers and Co/Ni multilayers were deposited epitaxially onto Cu(001) and Pt(111) substrates, respectively. By tailoring the effective anisotropy, spin reorientation transitions (SRTs) are employed to probe the orientation of the DMI vector by measuring the spin structure of domain walls on both sides of the SRTs. The interfacial DMI is found to be sufficiently strong to stabilize chiral Néel walls in the out-of-plane magnetized regimes, while achiral Néel walls are observed in the in-plane magnetized regimes. These findings experimentally confirm that the out-of-plane component of the DMI vector is insignificant in these fcc(001) and fcc(111) oriented interfaces, even in the presence of atomic steps. ; This work has been supported by the NSF (Grants No. DMR-1610060 and No. DMR-1905468) and the UC Office of the President Multicampus Research Programs and Initiatives (Grant No. MRP-17-454963). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contract No. DE-AC02-05CH11231. Work at GU has been supported in part by SMART (Grant No. 2018-NE-2861), one of seven centers of nCORE, a Semiconductor Research Corporation program, sponsored by National Institute of Standards and Technology (NIST). Work at the Kyung Hee University been supported by the National Research Foundation of Korea funded by the Korean Government (Grant No. NRF-2018R1D1A1B07047114). A.M. acknowledges support from the MINECO under the Project No. MAT2017-87072- C4-2-P and from Comunidad de Madrid under the Project No. S2018/NMT4321. E.G.M acknowledges support from MICINN (Spain) under Grant No. FIS2017-82415-R and from MECD (Spain) under Grant No. PRX17/00557. Y.W. acknowledges support from National Natural Science Foundation of China (Grants No. 11974079 and No. 11734006).

7 pags., 4 figs., 3 pags. ; The Dzyaloshinskii-Moriya interaction (DMI) is an antisymmetric exchange interaction that stabilizes chiral spin textures. It is induced by inversion symmetry breaking in noncentrosymmetric lattices or at interfaces. Recently, interfacial DMI has been found in magnetic layers adjacent to transition metals due to the spin-orbit coupling and at interfaces with graphene due to the Rashba effect. We report direct observation of strong DMI induced by chemisorption of oxygen on a ferromagnetic layer at room temperature. The sign of this DMI and its unexpectedly large magnitude—despite the low atomic number of oxygen—are derived by examining the oxygen coverage–dependent evolution of magnetic chirality. We find that DMI at the oxygen/ ferromagnet interface is comparable to those at ferromagnet/transition metal interfaces; it has enabled direct tailoring of skyrmion's winding number at room temperature via oxygen chemisorption. This result extends the understanding of the DMI, opening up opportunities for the chemisorption-related design of spin-orbitronic devices. ; This work has been supported by the NSF (DMR-1610060 and DMR-1905468) and the UC Office of the President Multicampus Research Programs and Initiatives (MRP-17- 454963). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under contract no. DE-AC02- 05CH11231. Work at GU has been supported, in part, by SMART (2018-NE-2861), one of seven centers of nCORE, a Semiconductor Research Corporation program, sponsored by the National Institute of Standards and Technology (NIST). A.M. and M.A.G.B. acknowledge support from MINECO (Spain) under the project no. MAT2017-87072-C4-2-P and from Comunidad de Madrid under the project no. S2018/NMT4321. The Jülich team acknowledges financial support from the DARPA TEE program through grant MIPR (# HR0011831554) from the DOI, the European Union H2020-INFRAEDI-2018-1 program (grant no. 824143, project "MaX— Materials at the exascale"), the Deutsche Forschungsgemeinschaft (DFG) through SPP 2137 "Skyrmionics" (project BL 444/16), the Collaborative Research Centers SFB 1238 (project C01), and computing resources at the supercomputers JURECA at Juelich Supercomputing Centre and JARA-HPC from RWTH Aachen University (projects jias1f and jara0197). R.L.C., A.K.S., and R.W. acknowledge financial support from the European Union via an International Marie Curie Fellowship (grant no. 748006). H.D. acknowledges the support of the National Key R&D Program of China (grant no. 2017YFA0303202) and the National Natural Science Foundation of China (grant nos. 11734006 and 51571109). E.G.M. acknowledges support from MINECO (Spain) under grants MAT2014-52477 and FIS2017-82415-R and from MECD (Spain) under grant PRX17/00557