Spin dynamics in an ultrathin Fe film in the vicinity of the superparamagnetic/ferromagnetic phase transition

• Epitaxially grown bcc Fe films on GaAs (100)-{4 × 6} were investigated at room temperature by in situ Brillouin light scattering. Remarkably we observed spin modes in the superparamagnetic regime for thicknesses far below the critical thickness of dc ≅ 4 ML at which ferromagnetism occurs. These modes are shown to correspond to the intrinsic modes of the physically separated Fe nanoclusters coupled by dipolar interactions. Furthermore we observed the influence of critical spin fluctuations in the vicinity of the phase transition as evidenced by an abrupt increase in spin wave peak linewidth and a sharp decrease in spin wave frequency with decreasing film thickness d in the ferromagnetic regime.

Subject headings

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Keyword

arsenic

ferromagnetic material

gallium

iron

acceleration

article

film

magnetism

molecular dynamics

molecular interaction

phase transition

thickness

Publication and Content Type

ref (subject category)

art (subject category)