Remanence due to Wall Magnetization and Counterintuitive Magnetometry Data in 200-nm Films of Ni

Abstract

200-nm-thick Ni films in an epitaxial Cu/Ni/Cu/Si(001) structure are expected to have an in-plane effective magnetic anisotropy. However, the in-plane remanence is only 42%, and magnetic force microscopy domain images suggest perpendicular magnetization. Quantitative magnetic force microscopy analysis can resolve the inconsistencies and show that (i) the films have perpendicular domains capped by closure domains with magnetization canted at 51 degrees from the film normal, (ii) the magnetization in the Bloch domain walls between the perpendicular domains accounts for the low in-plane remanence, and (iii) the perpendicular magnetization process requires a short-range domain wall motion prior to wall-magnetization rotation and is nonhysteretic, whereas the in-plane magnetization requires long-range motion before domain-magnetization rotation and is hysteretic.

Magnetic ripple domain structure in FeGa/MgO thin films

“…Magnetic force microscopy images presented in Fig 2a) shows lines on the film surface, interpreted as magnetic domain walls, separating areas without contrast, indicating that M is confined in the plane, and also some tip induced features; the image displayed in Fig 2b, taken for film 24-20, shows a fine structure which is not observed in the areas separated by the domains walls of the image 2a for film [13][14][15][16][17]. Fig 2c and 2d shows the same kind of magnetic contrast, revealing a non uniform magnetic configuration, in more detail for films with 28-56 and 28-21, respectively.…”

“…A consequence of non-homogeneous domain structure concerns the magnetization curves: if M has some degree of out-of-plane component or non-collinear distribution, the remanent magnetization M r has to be lower than the saturation value M s [8,13,14]. Figure 3(a) shows M vs µ 0 H for a maximum applied field of 9 T along the in-plane easy direction.…”

“…The overlap between orbitals of O and Fe metal induces large values for the interface anisotropy constant K s [10], and the ME contribution could be also used to manipulate the magnetic anisotropy if the film is grown onto a ferroelectric layer [11], besides of the modification of the electronic structure by the application of electric field [12]. The study of the magnetic domain configuration in thin films is a tool to insight about the presence of competing interactions, demonstrating the role of volume, as for instance the ME energy due to the coupling between magnetic moment and strain [13], as well as interface contributions [14] to the total magnetic anisotropy, in domain structures not observed in bulk materials. In polycrystalline films, the magnetization can be not homogeneous, generating the effect known as magnetization ripple [15].…”

Reversal mechanism, switching field distribution, and dipolar frustrations in Co/Pt bit pattern media based on auto-assembled anodic alumina hexagonal nanobump arrays

“…Indeed 100 nm domain periods would require 20 to 40 repeats in a strongly coupled thin film [30]. Nevertheless, it is interesting to note that a well-ordered stripe configuration in strongly coupled PMA thin films is only observed after in-plane field ac demagnetization [30,46]. Here all demagnetization processes, with a careful orientation of the external field to as close as possible to the normal to the film have led to a stripe state.…”

Rotation of stripe domains in a sputter deposited Tb-Fe-Ga thin film

“…Stripe domains and their rotation have been recently observed and studied in epitaxially grown thin films [9,10,11,12] displaying very high crystalline quality, obtained by advanced deposition methods, which are difficult to implement in a device-production process.…”