Simultaneous observation of the smoke signals during the growth of bcc Fe on the Ag(100) surface

Abstract

Simultaneous observation of the surface magneto-optic Kerr effect (SMOKE) and reflection high-energy electron diffraction (RHEED) intensity oscillation was done during the epitaxial growth of bcc Fe on fcc Ag(100) surface. The SMOKE system using the high-frequency (100 kHz) ac method has a high sensitivity (10−4 deg) and is able to obtain an absolute value of the Kerr rotation angle (φK ). φK of Fe/Ag(100) was measured at room temperature under magnetic fields of 0 and 100 Oe. When film thickness (d) is thicker than five monatomic layers (ML’s), φK of the longitudinal Kerr effect at 100 Oe increases with increasing d. No longitudinal SMOKE signal, however, was observed below 5 ML, while a polar Kerr signal was observed only in the range of 4 ML<d<5 ML. This suggests that the magnetic easy axis changes from perpendicular to in-plane at 5 ML, and below 4 ML the film is hardly magnetized by 100 Oe because of its high coercivity. These properties are discussed in relation to the crystal growth mechanism.