Suchergebnisse

© 2018 Author(s). This article is distributed under a Creative Commons Attribution (CC BY) License ; Spintronics exploits the magnetoresistance effects to store or sense the magnetic information. Since the magnetoresistance strictly depends on the magnetic anisotropy of a system, it is fundamental to set a defined anisotropy to the system. Here, we investigate half-metallic La0.67Sr0.33MnO3 thin films by means of vectorial Magneto-Optical Kerr Magnetometry and found that they exhibit pure biaxial magnetic anisotropy at room temperature if grown onto a MgO (001) substrate with a thin SrTiO3 buffer. In this way, we can avoid unwanted uniaxial magnetic anisotropy contributions that may be detrimental for specific applications. The detailed study of the angular evolution of the magnetization reversal pathways and critical fields (coercivity and switching) discloses the origin of the magnetic anisotropy, which is magnetocrystalline in nature and shows fourfold symmetry at any temperature ; S.K.C. acknowledges Programme International de Coopération Scientifique (PICS) du CNRS under Grant No. 6161 and SIMEM Doctoral School at Universite de Caen Normandie for financial support. IMDEA-Nanociencia acknowledges support from the "Severo Ochoa" Program for Centres of Excellence in R&D (MINECO, Grant No. SEV-2016-0686). F.A., J.C., and P.P. acknowledge the support of Spanish MINECO Project Nos. FIS2015-67287-P and FIS2016-78591-C3-1-R and the Comunidad de Madrid through Project NANOFRONTMAG CM. This project has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement Nos. 737116 (byAxon) and 654360 NFFA-Europe

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 Gr ; This 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)

Taming the magnetic anisotropy of lanthanides through coordination environments is crucial to take advantage of the lanthanides properties in thermally robust nanomaterials. In this work, the electronic and magnetic properties of Dy-carboxylate metal–organic networks on Cu(111) based on an eightfold coordination between Dy and ditopic linkers are inspected. This surface science study based on scanning probe microscopy and X-ray magnetic circular dichroism, complemented with density functional theory and multiplet calculations, reveals that the magnetic anisotropy landscape of the system is complex. Surface-supported metal–organic coordination is able to induce a change in the orientation of the easy magnetization axis of the Dy coordinative centers as compared to isolated Dy atoms and Dy clusters, and significantly increases the magnetic anisotropy. Surprisingly, Dy atoms coordinated in the metallosupramolecular networks display a nearly in-plane easy magnetization axis despite the out-of-plane symmetry axis of the coordinative molecular lattice. Multiplet calculations highlight the decisive role of the metal–organic coordination, revealing that the tilted orientation is the result of a very delicate balance between the interaction of Dy with O atoms and the precise geometry of the crystal field. This study opens new avenues to tailor the magnetic anisotropy and magnetic moments of lanthanide elements on surfaces. ; The ALBA synchrotron is acknowledged for providing beam time at BOREAS beamline (proposal number 2015091454). This project has received funding from the European Research Council (ERC, grant 766555) and Marie Sklodowska-Curie Actions (MSCA, project 894924) under the European Union's Horizon 2020 research and innovation programme. This work has been financed by the Spanish Ministerio de Economía, Industria y Competitividad (projects FIS2016-78591-C3-1-R, RTI2018-097895-B-C42, MAT2016-78293-C6-2-R, MAT2017-85089-C2-1-R, and PID2019-107338RB-C65); the Comunidad de Madrid (Projects S2013/MIT-2850, P2018/NMT4321, and S2018/NMT-4367); the European Regional Development Fund (ERDF) under the program Interreg V-A España-Francia-Andorra (Contract No. EFA 194/16 TNSI); and "Severo Ochoa" Programme for Centres of Excellence in R&D (grants SEV-2016-0686, and SEV-2017-0706).