Magnetic force microscopy investigation of the static magnetic domain structure and domain rotation in Fe-x at. %Ga alloys

Abstract

; et al., "Magnetic force microscopy investigation of the static magnetic domain structure and domain rotation in Fe-x at. %Ga alloys," Appl. Phys. Lett. 95, 152511 (2009); http://dx

Magnetic domain observations in Fe–Ga alloys

“…1 shows typical magnetic domain patterns of all three samples. These patterns are similar to the maze domain patterns reported by Bai et al [1,2], Zhou et al [19] and Song et al [20]. Contrary to the reported correlation between the domain size and the sample composition [1,2], it was found that domain patterns vary in size and structure within the same sample.…”

“…out-of-plane anisotropy. Contrary to the belief that this anisotropy is due to the presence of nanoscale heterogeneities [1,2] (Bai et al, 2005(Bai et al, , 2009), we show that it is due to a damaged surface layer caused by standard mechanical polishing. The surface conditions in Fe-Ga alloys are more sensitive to stress-induced damage than in pure a-Fe.…”

“…Hua et al [24] showed that a strong surface anisotropy can induce dense stripe domains in bulk materials, akin to those observed in Fe-Ga. Moreover, the similarity in the maze domain structure due to surface stresses in Fe-Si [23] with the Fe-Ga domain structure reported in [1,2,19,20] necessitates a re-evaluation of the Fe-Ga domain structure. We will demonstrate in this paper that an alternative polishing procedure allows observation of the true domain patterns, as expected from quality factor arguments.…”

“…The higher magnetostriction of Fe-Ga, however, will increasingly support the formation of elastically compatible domains to reduce the magnetostrictive self energy, and will render the material more sensitive to lower mechanical stresses when compared to pure iron. On a (0 0 1)-surface of Fe-Ga, one would expect to observe domains that are magnetized along the four surface-parallel easy directions Magnetic force microscope images [1,2,19,20] of these alloys, however, revealed highly complex and heterogeneous domains. Often, these domains are of a maze-character that is typical for magnetic films with out-of-plane anisotropy [14].…”

“…In contrast, the MFM study of Bai et al [1] showed a complex domain structure for x = 12, 20, and 25. In more recent work [2], Bai et al imaged complex domain patterns and showed that the out-of-plane anisotropy leading to the maze-like complex domains increases with increasing Ga concentration. It was noted that the domain irregularities under an applied magnetic field did not fit conventional domain growth or magnetization rotation mechanisms [14] and the unconventional magnetization rotation mechanism was explained to be due to the presence of heterogeneities in the A2 matrix.…”