We investigated the growth process and magnetic properties of iron deposited on Si 3N 4/Si(111)-(8×8) and clean Si(111)-(7×7) substrates by scanning tunneling microscopy, x-ray magnetic circular dichroism, and the magneto-optical Kerr effect measurements. These experiments reveal that, on clean Si(111)-(7×7), 1.6-monolayer (ML) Fe forms iron silicide with a very small spin magnetic moment of m spin=0.17 μ B, whereas 1.6-ML Fe on Si 3N 4/Si(111) has a much larger spin magnetic moment of m spin=2.62 μ B, which is enhanced compared with that of bcc bulk Fe (2.2 μ B). The Si 3N 4 surface is found to suppress the silicide formation effectively. Because of weak interaction between Fe and Si 3N 4 and possibly the mismatch of the lattice constant, Fe deposited on Si 3N 4/Si(111) grows as nanoparticles that exhibit superparamagnetism. Above 7.5 ML, most of the nanoparticles locate very closely to each other and become ferromagnetic.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - May 14 2012|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics