Extracting the hysteresis loops of magnetic interfaces from optical second-harmonic intensity measurements

Abstract

Surface-and interface-sensitive optical techniques, such as optical secondharmonic generation (SHG), allow the buried interfacial structure of centrosymmetric materials to be explored through thin capping layers, and magnetic SHG (MSHG) extends this to magnetic interfaces. However, the variation of the MSHG intensity with magnetic field does not measure hysteresis loops directly, because the loops are displaced by an amount dependent on the crystallographic response and its phase difference with respect to the magnetic response, and also because there is a quadratic magnetization contribution to the SH intensity that may be significant. Two new procedures are reported for extracting hysteresis loops directly from the MSHG intensity. The first is applicable to all magnetic interfaces, including exchange-biased structures, where the saturation magnetization for positive and negative magnetic fields is equal and opposite. The second applies to all centrosymmetric hysteresis loops. These procedures correct for the quadratic response, allowing experimental geometries to be chosen that maximize the magnetic contribution, thus improving the signal-to-noise ratio and the sensitivity of the technique.

Temperature-dependent magnetic second-harmonic generation from Fe nanostructures grown on vicinal W(110)

“…1 and 2. 31 For the 0.75 ML Fe sample, this has the additional consequence that the coherent contributions of the magnetic components partially destructively interfere, and thus the contrast increases when this contribution is switched off above T c for the second component (Fig. 2, right column).…”

“…(5) or (6). However, such a contribution would also produce an acentric magnetization loop, which the use of type I extraction of McGilp et al 10,31 would reveal. No evidence of a significant magnetoelastic contribution was found for this material system.…”

Second-Harmonic Generation Studies of Inhomogeneous Magnetization Distributions in Thin Garnet Film

“…Provided relation describes the remagnetization process in lm with perpendicular magnetic anisotropy, which can be associated with the unimplanted lm volume of H sat ≈ 1 kOe. The remaining contribution is described by normalized sigmoidal function M 2 (H) of the form [10]…”

Magnetic second-harmonic generation from interfaces and nanostructures

“…Right panels: extracted loops assuming a centrosymmetric magnetic response. Solid lines are fits to the extracted loops using sigmoidal curves (after [24]). …”

“…Fig. 5 shows that, for 3 ML Fe, the quadratic term introduces turning points in the MSHG A c c e p t e d m a n u s c r i p t -7 -response, but that this can be dealt with using two different approaches and the magnetic hysteresis loop successfully extracted [24].…”