Perpendicular anisotropy detected by transversely biased initial susceptibility via the magneto-optic Kerr effect inFexSi1−x<

Abstract

We studied experimentally and theoretically the perpendicular anisotropy and the stripe-domain structure in both Fe x Si 1Ϫx thin films and Fe x Si 1Ϫx /Si multilayers, the latter being in the low-modulation-length regime (0.4 nmϽϽ7 nm). The experimental study was made by means of the transversely biased initial susceptibility t␤ via the magneto-optic Kerr effect. The samples under study were prepared by dc triode sputtering at T S ϭ300 K. It is found that the appearance of stripe domains is more pronounced for decreasing as x remains constant and may be caused by both the increase in effective magnetic thickness and the reduction in effective magnetization as decreases. For multilayers with ϭ0.4 nm, the observed field dependence of t␤ Ϫ1 is similar to that found in homogeneous thin films when weak stripe-domain structures arise as a consequence of the existence of perpendicular anisotropy K N . We propose a quasistatic one-dimensional model to explain the behavior of t␤ Ϫ1 when stripe domains are present, and we analyze the critical occurrence of stripe domains. We calculated the so-called pseudo-uniaxial anisotropy field H Ks , associated with the stripes, in two extreme cases: exchange-driven susceptibility or magnetic free poles ͑nonzero divergence in the bulk͒. The latter case agrees better with experiment. We found that perpendicular anisotropy is not exclusive of a well-defined multilayer structure; i.e., K N arises even when there are no interfaces in the volume. By setting the experimental saturation field H s ͑obtained by hysteresis loops͒ into our model, we obtain both the perpendicular anisotropy constant K N ϭ10 4 -10 5 J/m 3 and the critical thickness t c for the occurrence of a stripe-domain structure. Some possible sources of perpendicular anisotropy are discussed, for example, the associated isotropic compressive stress , whose contribution is found to be ͉K N ͉ magnetoel Ϸ1.5-4.5ϫ10 4 J/m 3 .

Perpendicular magnetic anisotropy in Nd-Co alloy films nanostructured by di-block copolymer templates

“…20,21 Stripe domains tend to align along the direction of the last saturating field resulting in an almost isotropic in-plane magnetic behaviour, that is, magnetic films with stripe domains display the so called in-plane "rotatable" anisotropy. 37,38 This is indeed the case for the loops displayed in Fig. 3 and H C HA ¼ 490 Oe).…”

“…The in-plane uniaxial anisotropy field (H K jj ) of these 45 nm Nd-Co films is H K jj ¼ 380 Oe, calculated from the slope of the hard axis loop. On the other hand, "rotatable" anisotropy produces a "pseudouniaxial" anisotropy field (H K rot ) that is given 38 by…”

Perpendicular magnetic anisotropy in amorphous NdxCo1−x thin films studied by x-ray magnetic circular dichroism

“…The measurement in the H field orientation is what is called a transcritical loop. This kind of loop appears above a critical thickness whose size depends on the magnetization and the PMA energy of the film [6,41,[46][47][48]. A rough estimation of the PMA energy in this sample based on its XMCD hysteresis loops and magnetization yields a value not far from 1.3×10 6 J m −3 , which is similar to that obtained using a more precise method in a similar but thicker sample [17,41,49].…”

Coercive and anisotropy fields in patterned amorphous FeSi submicrometric structures

“…10 The magnetic behavior has been characterized by magneto-optical transverse Kerr effect ͑TKE͒ measurements in a experimental setup reported elsewhere. 11 The hysteresis loops reveal the presence of an uniaxial magnetic anisotropy. The compositional dependence of the coercive field (H C ) measured along the easy axis is shown in Fig.…”