Bulklike behavior of magnetoelasticity in epitaxial Fe1−xGax thin films

Abstract

Bulk Fe 1−x Ga x alloys present a strong sensitivity of the magnetostrictive properties with Ga content with maximum magnetostriction near x = 0.19. Here, we present magnetoelastic coefficients measured by the cantilever method on Fe 1−x Ga x thin films grown by molecular beam epitaxy on GaAs(001). We find that Ga-dependent magnetoelastic coefficients in nanometer thin films are comparable in magnitude to the respective bulk values. Moreover, we compare thin films with a tetragonal structure due to a slightly preferential alignment of Ga pairs along the growth direction with and a cubic structure. It turns out that magnetoelastic coefficients are unaffected by a preferential alignment of Ga pairs along the growth direction.

Unveiling the Different Physical Origins of Magnetic Anisotropy and Magnetoelasticity in Ga-Rich FeGa Thin Films

“…Therefore, while the magnetic anisotropy seems to be related to the local range order (Ga pairs and tetragonal distortion) in Ga-rich Fe 100– x Ga x alloys, the magnetoelastic behavior can be understood considering the distribution of grains, i.e., medium range order. This result goes in the same direction as a previous report by Barturen et al in epitaxial Fe 100– x Ga x thin films with a Ga content near 19 at. %.…”

“…medium range order. This result goes in the same direction than a previous report on Barturen et al 15 in epitaxial Fe 100-x Ga x thin films with a Ga content near 19 at. %.…”

“…The thickness dependence of ME coefficients in epitaxial thin films is usually explained by considering surface or second order strain effects . However, no significant variation for B 1 and B 2 with respect to the bulk values has been reported for FeGa epitaxial films . On the other hand, because B eff can be expressed in terms of the crystallite axis distribution, changes of the values of the magnetostriction can be related to variations in the crystal texture of the films .…”

“…Over the last years, the metallic FeGa system has attracted a huge interest due to the discovery in 2000 of a large magnetostriction in these free rare-earth alloys [3][4] . Many of the published works have been devoted to the understanding of the origin of this enhanced magnetostriction in contrast with pure Fe [5][6][7][8][9][10][11][12][13][14][15] . It is remarkable that the largest deformation in Fe can be reached in the [100] direction with a (3/2) 100 value of 45 ppm 16 , whereas in FeGa alloys reaches up to 430 ppm 7 .…”

“…Over the past years, the metallic FeGa system has attracted huge interest due to the discovery in 2000 of a large magnetostriction in these free rare-earth alloys. , Many of the published works have been devoted to the understanding of the origin of this enhanced magnetostriction in contrast with pure Fe. − It is remarkable that the largest deformation in Fe can be reached in the [100] direction with a (3/2)­λ 100 value of 45 ppm, whereas in FeGa alloys it reaches 430 ppm . The investigations of FeGa thin films have shown the strong impact that the different structural orderings from long to local range have on the magnetic properties of these alloys. ,− Closely related to these investigations are those about the origin of the magnetic anisotropy in either the in-plane or out-of-plane directions of FeGa thin films. ,,,− There is still some controversy about the origin of magnetoelasticity in FeGa with works pointing to an intrinsic effect, , or to nanoheterogeneities that induce some tetragonal distortion of the matrix .…”