Magnetoelasticity of Fe1−xGax thin films on amorphous substrates

Abstract

In this work, we study the magnetoelastic behavior of Fe 1−x Ga x (0.11 < x < 0.19) thin films, grown on glass and oxidized Si(100) amorphous substrates, that present an isotropic crystalline texture in the film plane. The magnetoelastic coupling coefficients are obtained through the cantilever deflection technique. We find that the magnetoelastic response is larger for samples grown on glass with respect to those grown on Si(100), and such a response increases for larger Ga concentrations for both substrates used. Furthermore, the increasing substrate temperature during growth does not appear to have a significant effect on magnetoelastic behavior of samples grown on Si(100). From a model that takes into account the elastic grain interaction for isotropic systems, we are able to describe the experimentally observed behavior. We find that the magnetoelastic response of the samples grown on glass are well described by the Voigt model, while the samples on Si(100) present an intermediate response between the Voigt and Reuss models.

Microstructural contribution to the magnetic anisotropy in Fe 1 − x <

“…Also, a small additional peak (marked with blue asterisks) corresponding to the reflection (222) of the D0 3 ordered phase is observed for FG30-Si-RT and FG30-Si-250 samples. We have discussed the occurrence of this reflection in previous works [14,40], and we concluded that the coexistence of phases A 2 + D0 3 is expected for this concentration in the metastable phase diagrams of the Fe 1−x Ga x alloy. It is interesting to note that the increase in Ga promotes an improvement in the crystallinity of the samples that is characterized by fine and intense peaks (see blue diffractograms), probably favored by the A 2 + D0 3 metastable phase.…”

“…The films were deposited in a vacuum chamber under base pressure < 1.5 × 10 −6 Torr, in which the argon pressure was set at 2.7 mTorr, and the sputtering power at 20 W. The deposition process was previously optimized [14,25,35] resulting in the following deposition rates for the respective target: R 0.17 ∼ 0.136 nm s −1 , R 0.25 ∼ 0.144 nm s −1 and R 0.3 ∼ 0.156 nm s −1 . The films studied in this work were labeled taking into account the type and temperature of the substrate, in addition to the nominal target Ga concentration, as summarized in table 1.…”

“…Structural phases present in this system are also Ga-dependent. Fe 1−x Ga x alloys (0.11 < x < 0.19) usually present an A2 structure [14], or even the D0 3 nanoprecipitation phase can be obtained under slow cooling [15,16]. Ga-rich Fe 1−x Ga x alloys are unusually reported because their phase structures become very complex when the Ga content exceeds x = 0.2 [17][18][19][20].…”