Large wave vector spin waves and dispersion in two monolayer fe on w(110)

Area of Science:

• Condensed Matter Physics
• Materials Science
• Surface Science

Background:

• Spin waves (SW) are fundamental magnetic excitations in materials.
• Understanding SW behavior in thin films is crucial for spintronics.
• Previous studies lacked detailed dispersion measurements for ultrathin Fe films.

Purpose of the Study:

• To measure surface spin-wave dispersion in a two-monolayer Fe film on W(110) up to the Brillouin zone boundary.
• To compare experimental SW energies with theoretical predictions and bulk Fe values.
• To investigate the factors influencing SW behavior in ultrathin magnetic films.

Main Methods:

• Utilized spin-polarized electron energy loss spectroscopy (SPEELS).
• Performed measurements on a two-monolayer (ML) Fe film epitaxially grown on a W(110) substrate.
• Recorded spectra at room temperature.

Main Results:

• Observed distinct surface spin-wave peaks in the SPEELS spectra.
• Found that SW energies in the 2 ML Fe film are significantly lower than those in bulk Fe.
• Experimentally determined SW dispersion up to the surface Brillouin zone boundary.

Conclusions:

• The reduced SW energies indicate a weakened exchange interaction in the ultrathin Fe film compared to bulk Fe.
• The findings challenge existing theoretical models for SWs in such confined systems.
• This work provides critical experimental data for understanding magnetism in low-dimensional Fe systems.