Non‐linear magnetoelastic coupling in monolayers: Experimental challenges and theoretical insights

Abstract

Recent results of experimental studies on magnetoelastic coupling in epitaxial monolayers are compiled and discussed in view of theoretical work. The observation of non-bulk like magnetoelastic coupling in strained systems in experiment and theory is ascribed to an effective and strain-dependent magnetoelastic coupling. It is described as a second-order strain contribution to the energy density. We comment on the importance of inhomogeneous strain and of its relaxation for the magnetic anisotropy of nanostructures.

The impact of structural relaxation on spin polarization and magnetization reversal of individual nano structures studied by spin-polarized scanning tunneling microscopy

“…Although it is well established for bulk samples and for atomic layers that bond-length variations and magnetic anisotropy are intimately linked via magneto elastic coupling [29,[98][99][100][101][102], the reliable application of the corresponding description for individual nano structures has not been established yet. To appreciate this situation it is necessary to recall that the theoretical modeling of magneto elasticity is very demanding, even for bulk samples and even more so for strained atomic layers [102]. Local variations of bond lengths, such as expected here, may bring this description to its limitations.…”

Bulklike behavior of magnetoelasticity in epitaxial Fe1−xGax thin films

“…where ii refers to the strain in the i direction, i j is the shear strain associated with directions i j, α i represents the direction cosine of the magnetization associated with the i direction (where i = 1, 2, 3 corresponds to x, y, z, respectively). The dots indicate that higher-order terms are omitted, but may be important, e.g., in systems which are under significant epitaxial strain [16,24]. By considering…”

Effect of mesoscopic misfit on growth, morphology, electronic properties and magnetism of nanostructures at metallic surfaces

“…41, has developed ever since into a reliable source of quantitative data on stress with an astonishingly high sensitivity in the sub-monolayer coverage regime [10,135,201,[207][208][209]. The high sensitivity of the measurement scheme is evident from its successful application also to the measurement of magneto elastic stress in monolayers [10,68,209,210], where the magnitude of stress is roughly three orders of magnitude smaller as compared to stress due to epitaxial misfit in the percent range.…”

“…Lattice strain and magnetism are intimately linked by the magneto elastic coupling, which describes the strain dependence of the magnetic anisotropy [10,68,137,138]. In short, an anisotropic lattice strain is often the driving force for a change of the easy axis of magnetization in epitaxial layers, away from the respective bulk direction.…”