Nanospectroscopy

Welcome to XPEEM and LEEM @ Elettra

The study of nanostructured materials requires analytical methods that combine X-ray spectroscopy with electron microscopy. The Nanospectroscopy beamline at Elettra operates a state-of-the-art spectroscopic photoemission and low energy electron microscope (SPELEEM). This powerful instrument offers a wide range of complementary methods providing structural, chemical and magnetic sensitivity. The lateral resolution of the microscope currently approaches few tens nm. The microscope is served by a high photon flux beamline, which can deliver elliptically polarized photons in the range 50 eV to 1000 eV. Research applications are targeted to Surface and Materials Sciences, addressing issues related to chemical and magnetic characterization of surfaces, interfaces, thin films, and nanostructures.

Research Highlights | Publications | Applications | Agenda | Calendar | End-station

Fine tuning of FM/AFM interface magnetic anisotropy

We studied epitaxial NiO/Fe(110) and show the spin orientation of the AFM domains in the oxide layer is controlled by the magnetization in the FM layer. The ability to modify the AFM spin orientation via Fe film thickness and temperature opens up possibilities for applications.
M. Ślęzak et al., Nanoscale 12, 18091 (2020); doi: 10.1039/d0nr04193a

Unveiling the formation of epitaxial graphene on cobalt

PEEM and LEEM enabled imaging the structural transformation that graphene on cobalt undergoes at temperatures above 500°C, from a rotationally-incoherent, defective layer to an epitaxial one.The structural transformation takes place via the growth and propagation of mesoscopic carbidic islands and involves the dissolution and recondensation of carbon.
M. Jugovac et al., Carbon 152, 489-496 (2019).

In-Gap States and Band-Like Transport in Memristors

Laterally-resolved soft X-ray resonant photoelectron spectromicroscopy enabled direct access to the electronic structure of a conductive filament in an epitaxial memristive device. Oxygen vacancies in SrTiO_3–x were found to induce the formation of in-gap states that impact the shape of the conduction band.
C. Baeumer et al., Nano Lett. 19, 54–60 (2019).

Writing the magnetic state with carbon monoxide

We devised a new method to graft chemo-magnetic patterns by depositing atomic carbon through electron stimulated molecular dissociation. To do this, an ultra-thin cobalt film is exposed it to CO while irradiating the surface with an intense, micro-focused low energy electron beam.
P. Genoni et al., ACS Applied Materials & Interfaces 10(32), 27178–27187 (2018).

Subfilamentary Networks in Memristive Devices

In-operando XAS-PEEM gives access to the microscopic origin of resitance variability in memristior devices based on transition metal oxides. Upon switching, the spatial rearrangement of oxygen vacancies results in variations of their local concentration and shape of the conductive filament bridging the metal electrodes.
C. Baeumer et al., ACS Nano 11, 6921 (2017).

Graphene and h-BN by a Single Molecular Precursor

The fabrication of graphene h-BN layers is rather challenging. We report here a novel bottom-up approach to obtain a continuous almost free-standing hexagonal single layer with perfectly merging graphene and hexagonal boron-nitride domains using only one molecular precursor.
S. Nappini et al., Adv. Funct. Mater. 7, 1120 (2016).

Stable magnetic skyrmions at room temperature

Magnetic skyrmions are chiral spin structures with a whirling configuration. By employing x-ray magnetic circular dichroism photoemission electron microscopy, we imaged for the first time the chiral Néel internal structure of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures at room temperature and zero external magnetic field.
O. Boulle et al., Nat. Nanotech. 11, 449 (2016).

Fragmentation of magnetism in dipolar spin ice

Few cases exist where a system remains disordered as a gas or a liquid, even at the lowest temperatures accessible experimentally. Systems that simultaneously exhibit different order states are even rarer. Such a phase, “liquid” and “solid” at the same time, has been recently observed in a magnetic metamaterial, artificial spin ice.
B. Canals et al., Nat. Comm. 7, 11446 (2016);

Island Ripening in a catalytic reaction

We have investigated a reaction-controlled ripening process of ultrathin vanadium oxide on Rh(111) during catalytic methanol oxidation. Under reaction conditions, neighboring vanadium oxide islands move towards each other and coalesce. This quasi-macroscopic ripening is explained by a polymerization-depolymerization mechanism which is sensitive to gradients in the adsorbate coverages.
M. Hesse et al., Phys. Rev. Lett. 115, 136102 (2015).

Fabrication of 2D heterojunction in graphene

Irradiation with very-low energy nitrogen ions is used to locally induce substitutional doping in graphene. Irradiated and non-irradiated areas are separated by a sharp boundary, stable up to 750 °C. Our experiments pave the way to the lithographic control of the electronic properties of graphene and provide a proof-of-principle for the fabrication of graphene-based heterojunctions.
A. Sala, Small 11(44), 5927–5931 (2015).

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Beamline developments

SPELEEM microscope upgrade

The beamline end-station was largely upgraded in fall 2020, in order to ensure competitiveness for the future years. In particular, the electron energy analyzer was replaced by a new model with larger radius, permitting to reach energy resolution better than 100 meV in imaging mode and 60 meV in micro-spot spectroscopy. In addition to the analyzer, the SPELEEM microscope hardware has been improved in several other areas, in particular, the sample holder and its cryostat. The sample manipulator allows now azimuthal rotation, targeting a vectorial mapping of magnetization using XMCD-PEEM. Further, the alignment and remote manipulation of sample and microscope apertures and slits is now possible. The beamline staff welcomes proposals exploring these new capabilities and invites users to discuss ideas for future experiments.

Coherent diffraction imaging at the SPELEEM

We demonstrated the feasibility of coherence diffraction imaging (CDI) in reflection geometry at the PEEM setup. The possibility of routinely performing CDI can make the Nanospectroscopy end-station an unicum in its kind and will greatly expand the capabilities of the end-station. The result will be the simultaneous acquisition of diffracted x-rays (CDI) and photoemitted electrons (XPEEM) giving complementary images of the same surface region. The CDI phase retrieval will be greatly simplified using the XPEEM image of the same region. Furthermore, CDI provides an alternative approach to photoemission. CDI offers much greater probing depth and it is not subject to the artifacts suffered by XPEEM in the case of insulating samples, in-situ application of electric and magnetic fields, etc.
Read the full paper on Ultramicroscopy.

A multi-method magnetic facility with a new UHV MOKE magnetometer

A custom-designed UHV MOKE (Magneto-Optical Kerr Effect) magnetometer is now available at the Nanospectroscopy beamline. This setup provides the experimental station with a unique facility combining sensitivity at the state of art (close to monolayer), UHV compatibility, and ability to work in tandem with the SPELEEM x-ray photoemission electron microscope at Elettra. The possibility to exchange samples between MOKE and SPELEEM is a distinctive feature of our instrument, which makes it unique in synchrotrons and is crucial for the goal of establishing a multi-method magnetic facility. The implementation and application of the setup is detailed in an article published in the Journal of Synchrotron Radiation. CERIC users can access the MOKE only by submitting CERIC proposals indicating Nanospectroscopy as beamline.

Detector Gating for Time Resolved Measurements

In order to exploit the pulsed structure of synchrotron radiation in stroboscopic experiments, the imaging detector of the PEEM needs to be gated. So far, gating has been done by applying a voltage pulse to the MCP output-plate, a solution that impacts negatively on the detector lifetime. We have developed a novel approach based on miniaturized electrode plates, which deflect the photoelectron beam inside the imaging column of the microscope so that it is either accepted or blocked in its path towards the detector. The gating device is optimized for installation on the Elmitec SPELEEM III microscope.The application of this set-up, which has been developed in collaboration with ALBA, is described in an article published in Ultramicroscopy.

NanoESCA beamline

A NanoESCA microscope (Omicron - Focus, GmbH) has been installed and commissioned on the Nanospectroscopy beamline second branch. The microscope is an electrostatic PEEM with double-pass hemispherical analyzer. The instrument is managed by an international consortium led by Forschungszentrum Jülich (Peter Grünberg Institute). The branchline has been open to Elettra general users in January 2012, with the name of NanoESCA. The NanoESCA website offers a wide perspective on the types of measurements that can be carried out with this instrument.

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User Area

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Proposal Submission

We invite users to discuss their proposals with the beamline contacts well in advance before the submission deadline. This is crucial for careful assessment of the experiment feasibility and may lead to improvements in the proposed experimental plan. In a restricted number of cases, it may be possible for you to arrange a test. For more info, please visit the user info section.

Call for proposals

The deadline for proposal submission for beamtime allocation is Wed, 15 Sep 2021
Read more...

All proposals will be performed with the SPELEEM microscope on the first beamline branch
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Access through CERIC

Nanospectroscopy is part of the CERIC-ERIC consortium. CERIC-ERIC offers access to more than 40 different and complementary state of the art techniques, distributed in 8 countries, with the submission of single or multi-technique proposals through a single entry point.

Last Updated on Saturday, 11 September 2021 00:17