Wolfgang WEBER

Wolfgang WEBER

Professeur, Magnetic Objects on the NanoScale (DMONS)wolfgang.weber@ipcms.unistra.fr
Station: +33(0)3 88 10 70 87, +33(0)3 88 10 70 02Office: 1048
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Research background

1988-1992: PhD student, RWTH Aachen (Germany). Study of interface states by spin-polarized photoemission.

1993-1995: Post-doc, IBM Rüschlikon (Switzerland). Study of ultrathin magnetic films and microstructures by spin-polarized scanning electron microscopy.

1995-2002: Senior scientist, ETH Zürich (Switzerland). Study of ferromagnetic thin films by time- and spin-resolved electron spectroscopy.

since 2002: Professor, U. Strasbourg

Academic background

Studies of physics in Cologne (Germany)
1988: Diploma degree in physics
1988-1992: PhD in physics at the RWTH Aachen (Germany)

Current researches

Spin-polarized electron reflection to understand the very particular behavior of the spin-dependent electron reflection from carbon-containing layers on ferromagnets (F. Djeghloul et al., Phys. Rev. B 89, 134411 (2014).). Our recent studies give strong evidence that this “breakdown”-behavior of the spin-dependent electron reflection is even more general and exists for many elements of the periodic system.

Study of the very high spin polarization of organic spinterfaces at room temperature. The presence of highly spin-polarized interface states at the ferromagnetic metal-organic interface does not seem to be limited only to conjugated organic systems which is usually believed (F. Djeghloul et al., J. Phys. Chem. Lett. 7, 2310 (2016).).

To design multifunctional devices using the rich palette of electronic properties proposed by molecular engineering, it is crucial for the organic spintronics research field to craft organic spinterfaces using molecules with an intrinsic property. However, in many cases the direct contact between ferromagnetic layer and molecules degrades the quality of the molecular layer. One solution to this problem is the use of a less reactive constituent in the multilayer structure, such as Cu, which separates the ferromagnetic layer from the molecules. Such a “protected spinterface” exhibits a very significant spin polarization and is thus still spintronically active (E. Urbain et al., Adv. Funct. Mater. 28, 1707123 (2018).). Of particular interest are the very “delicate” spin-crossover molecules (SCO) in which the spin state of the central metal ion can be toggled using external stimuli such as temperature and light.

To master the delicate interplay of electronic properties within a solid-state device, we will transpose fundamental materials science properties of protected spinterfaces to molecular nanospintronic device studies. For this we will utilize our novel 300-nm-diameter nanojunction process, based on nanosphere lithography, which works with entire in-situ grown heterostructures and does not expose the organic layer or the sample flanks to resist/solvents (K. Katcko et al., Adv. Funct. Mater. 31, 2009467 (2021).).

Publications

  • Direct observation of a highly spin-polarized organic spinterface at room temperature; F. Djeghloul et al., Sci. Rep. 3, 1272 (2013).
  • Breakdown of the electron-spin motion upon reflection at metal-organic or metal-carbon interfaces; F. Djeghloul et al., Phys. Rev. B 89, 134411 (2014).
  • Exchange bias and room-temperature magnetic order in molecular layers; M. Gruber et al., Nat Mater. 14, 981 (2015).
  • Spin-dependent hybridization between molecule and metal at room temperature through interlayer exchange coupling; M. Gruber et al., Nano Lett. 15, 7921 (2015).
  • High Spin Polarization at Ferromagnetic Metal−Organic Interfaces: A Generic Property, F. Djeghloul et al., J. Phys. Chem. Lett. 7, 2310 (2016).
  • Cu metal / Mn phthalocyanine organic spinterfaces atop Co with high spin polarization at room temperature; E. Urbain et al., Adv. Funct. Mater. 28, 1707123 (2018).
  • Encoding Information on the Excited State of a Molecular Spin Chain; K. Katcko et al., Adv. Funct. Mater. 31, 2009467 (2021).