First-principles investigation of spin-wave dispersions in surface-reconstructed Co thin films on W(110)

Abstract

We computed spin-wave dispersions of surface-reconstructed Co films on the W(110) surface in the adiabatic approximation. The magnetic exchange interactions are obtained via first-principles electronic-structure calculations using the Korringa-Kohn-Rostoker Green-function method. We analyze the strength and oscillatory behavior of the intralayer and interlayer magnetic interactions and investigate the resulting spin-wave dispersions as a function of the thickness of Co films. In particular, we highlight and explain the strong impact of hybridization of the electronic states at the Co-W interface on the magnetic exchange interactions and on the spin-wave dispersions. We compare our results to recent measurements based on electron-energy-loss spectroscopy [E. Michel, H. Ibach, and C.M. Schneider, Phys. Rev. B 92, 024407 (2015)]. Good overall agreement with experimental findings can be obtained by considering the possible overestimation of the spin splitting, stemming from the local-spin-density approximation, and adopting an appropriate correction.

Spin-resolved inelastic electron scattering by spin waves in noncollinear magnets

“…With the polarization of the beam parallel to the spin of the sample, we find only one active inelastic scattering channel, the down-up (m = −1). This is in agreement with the conventional wisdom that it takes a spin-flip process to create a spin wave, which is the picture familiar from (SP)EELS experiments [32,33,47], also found in our previous work [41]. For this model, the spectrum features a single and continuous spin-wave branch ( Fig.…”

“…The wave nature of the electron beam leads to the Fourier factor connecting the basis atoms in the unit cell (R μν = R ν − R μ ) and is responsible for the unfolding of the spin-wave modes [41]. The information about the spin excitations of the sample is contained in the imaginary part of the spin-spin correlation tensor…”

“…On the other hand, inelastic electron scattering has been applied with great success to study spin waves in ultrathin films [32][33][34][35][36][37][38][39][40][41][42], due to the large scattering cross section of the electrons. However, to the best of our knowledge, it has only been employed for ferromagnets.…”

Assessing different approaches to ab initio calculations of spin wave stiffness

“…Higher powers should be included in the fitting polynomial Eq. ( 17); employing just a simple quadratic fit as done, e.g., in [43] may not always be sufficient. In many cases, calculating the energy dispersion ǫ(q) is difficult or impractical (e.g., for multicomponent systems with substitutional disorder).…”

Complex magnetism of the two-dimensional antiferromagnetic Ge2F: from a Néel spin-texture to a potential antiferromagnetic skyrmion

“…The associated theoretical framework was presented in ref. 56 and 57 and used for various problems. 58,59 The spin-wave eigenvalues ω ( k ) and eigenvectors k are then obtained after diagonalization of the system's dynamical matrix in the reciprocal space.…”