VUV photoemission beamline

Welcome to the VUV

The VUV Photoemission beamline, a joint project of ISM-CNR and Elettra - Sincrotrone Trieste, offers advanced instrumentation for Italian and International condensed matter community. The VUV is designed primarily for surface and solid state experiments by high resolution photoemission. The research activity at the VUV photoemission beamline covers a wide range of scientific topics on the physics of metal and semiconductor surfaces and interfaces. In particular the following types of experiments can be carried out:

  • band mapping by high energy and angle-resolved photoemission; 

  • high resolution photoemission on core levels and valence band;

  • photoelectron diffraction.

Research highlights

Electronic States of Silicene Allotropes on Ag(111)

  
  Silicene, a honeycomb lattice of silicon, presents a particular case of allotropism on Ag(111). Silicene forms multiple structures with alike in-plane geometry but different out-of-plane atomic buckling and registry to the substrate. Angle-resolved photoemission and first-principles calculations show that these silicene structures, with (4×4), (√13×√13)R13.9°, and (2√3×2√3)R30° lattice periodicity, display similar electronic bands despite the structural differences. 

P. M. Sheverdyaeva et al., ACS Nano 11 (2017) 975.

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Asymmetric band gaps in a Rashba film system

  
  The joint effect of exchange and Rashba spin-orbit interactions is examined on the surface and quantum well states of Ag2Bi-terminated Ag films grown on ferromagnetic Fe(110). The system displays a particular combination of time-reversal and translational symmetry breaking that strongly influences its electronic structure. Angle-resolved photoemission reveals asymmetric band-gap openings, due to spin-selective hybridization between Rashba-split surface states and exchange-split quantum well states. 
  C. Carbone et al.Phys. Rev. B 93 (2016) 125409

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Silicene on Ag(111): A honeycomb lattice without Dirac bands


The discovery of (4×4) silicene formation on Ag(111) raised the question whether silicene maintains its Dirac fermion character, similar to graphene, on a supporting substrate. Previous photoemission studies indicated that the π band forms Dirac cones near the Fermi energy, while theoretical investigations found it shifted at deeper binding energy.  
S. Mahatha et al.Phys. Rev. B 89 (2014) 201416(R) 

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Energy-momentum mapping of d -derived Au(111) states in a thin film

  
  The quantum well states of a film can be used to sample the electronic structure of the parent bulk material and determine its band parameters. We highlight the benefits of two-dimensional film band mapping, with respect to complex bulk analysis, in an angle-resolved photoemission spectroscopy study of the 5d states of Au(111). Discrete 5d-derived quantum well states of various orbital characters form in Au(111) films and span the width of the corresponding bulk bands. 

P. M. Sheverdyaeva et al.Phys. Rev. B 93 (2016) 035113

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Spin-orbit interaction and Dirac cones in d-orbital noble metal surface states


Band splittings, chiral spin polarization, and topological surface states generated by spin-orbit interactions at crystal surfaces are receiving a lot of attention for their potential device applications as well as fascinating physical properties. Most studies have focused on sp states near the Fermi energy, which are relevant for transport and have long lifetimes. Far less explored, though in principle stronger, are spin-orbit interaction effects within d states, including those deep below the Fermi energy.  

R. Requist et al.Phys. Rev. B 91 (2015) 045432 

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Magnetization-dependent Rashba splitting of quantum well states at the Co/W interface


Exchange and Rashba spin-orbit interactions are expected to couple at ferromagnetic-metal/heavy-metal interfaces and influence their electronic structure. We examine these largely unexplored effects in Co(0001) films on W(110) by angle-resolved photoemission spectroscopy. We find breaking of inversion symmetry in the band dispersion of magnetic quantum well states along structurally equivalent directions of the Co films.  

P. Moras et al.Phys. Rev. B 91 (2015) 195410 

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User Area

Proposal Submission

We invite users and collabrators to discuss thier proposals with the beamline local contacts well in advance before the submission deadline. This is crucial for a careful assesment of the experiment feasibility and may lead to improvements in the proposed experimental plan. Our website provides a wealth of informaiton on experiment feasibilty and proposal submission. For more info, please vist the user info section.

Call for proposals

The deadline for proposal submission for beamtime allocation from January 1st to June 30th, 2017 will be September 15th, 2016.

News

Recently done

New manipulator

We introduced a new manipulator with following characteristics:
- Liquid He closed cycle cryostat
- Temperature range 9-450 K
- Linear motion along the X, Y, and Z axes
- Polar rotation with 0.1° accuracy
- Azimuthal rotation (±180°) with 0.01° accuracy.
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New high-temperature chamber available

This chamber serves also as fast entry chamber and allows sample preparation in high pressures (up to 10-3 mbar) and at high temperatures (above 2000°C) and their magnetization.
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Motorized azimuthal angle rotation

Fermi surfaces measurements are motorized, with asimuthal angle resolution below 0.01°.
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Ongoing developements

We have recently installed a new manipulator and changed the sample holders. Please ask your local contact for more details.

 
Last Updated on Friday, 02 October 2015 14:50