Layer-dependent magnetization at the surface of a band-ferromagnet

We present a theory to study the temperature-dependent behavior of surface states in a ferromagnetic semi-infinite crystal. Our approach is based on the single-site approximation for the \emph{s-f} model. The effect of the semi-infinite nature of the crystal is taken into account by a localized perturbation method. Using the mean-field theory for the layer-dependent magnetization, the local density of states and the electron-spin polarization are investigated at different tem...

A surface magnetoelectric effect is revealed by density-functional calculations that are applied to ferromagnetic Fe(001), Ni(001) and Co(0001) films in the presence of external electric field. The effect originates from spin-dependent screening of the electric field which leads to notable changes in the surface magnetization and the surface magnetocrystalline anisotropy. These results are of considerable interest in the area of electrically-controlled magnetism and magnetoel...

We present the results of an ab initio study of magnetic properties of Fe, Co and Ni surfaces. In particular, we discuss their electronic structure and magnetic exchange interactions (Jij), as obtained by means of a combination of density functional theory and dynamical mean-field theory. All studied systems have a pronounced tendency to ferromagnetism both for bulk and surface atoms. The presence of narrow-band surface states is shown to enhance the magnetic moment as well a...

We use a combination of density functional theory and Monte Carlo calculations to calculate the surface magnetization in magnetoelectric $\mathrm{Cr_2O_3}$ at finite temperatures. Such antiferromagnets, lacking both inversion and time-reversal symmetries, are required by symmetry to posses an uncompensated magnetization density on particular surface terminations. Here, we first show that the uppermost layer of magnetic moments on the $(001)$ surface remain paramagnetic at the...

We propose a method to determine the direction of surface magnetization and local magnetic moments on the atomic scale. The method comprises high resolution scanning tunneling microscope experiments in conjunction with first principles simulations of the tunneling current. The potential of the method is demonstrated on a model system, antiferromagnetic Mn overlayers on W(110). We expect that it will ultimately allow to study the detailed changes of magnetic surface structures...

The orientation of the magnetization of a Ni(110) surface was investigated using techniques with different probing depths. By making use of electron capture into excited states of fast He atoms, we found that the magnetization of the topmost surface layer is not aligned along the easy axes of Ni. However, for a 50 ML film Fe on Ni(110) we observed the magnetization of the topmost Fe surface layer is along the easy axes of Fe.

The structural and electronic properties of the surfaces of Sm(0001) and Eu/Gd(0001) were studied by scanning tunneling microscopy and spectroscopy at temperatures between 10 and 110 K. In both systems, an unoccupied surface state is observed that exhibits a temperature-dependent splitting into two states for Eu/Gd(0001), while it is unsplit on Sm(0001). This strongly indicates that the divalent outermost surface layer of Sm(0001) is non-magnetic despite the antiferromagnetic...

The Augmented Space Formalism coupled with Recursion method and Density Functional Theory based Tight-Binding Linear Muffin-Tin Orbitals have been applied for a first principles calculation of surface electronic and magnetic properties of body centered cubic Fe(001) and face centered cubic Co(001) and Ni(001). Nine atomic layers have been studied to see the trend of change in these properties from surface into the bulk. Surface magnetic moment has been found to be higher than...

The atomic interaction and magnetic properties of ultrathin Fe films grown on cleaved and polished MgO(100) surfaces were studied by conversion electron M\"{o}ssbauer spectroscopy (CEMS) in broad temperature range. Fe with different layer thickness was deposited on MgO substrates. The layers were formed on polished and cleaved substrate surfaces at RT. The analysis of the spectra showed no Fe-O$^{2-}$ interaction in MgO/Fe interface. Iron layers showed different magnetic anis...

We use symmetry analysis and density functional theory to characterize antiferromagnetic (AFM) materials which have a finite equilibrium magnetization density on particular surface terminations. A nonzero magnetic dipole moment per unit area or "surface magnetization" can arise on particular surfaces of many AFMs due to the bulk magnetic symmetries. Such surface magnetization plays an essential role in numerous device applications, from random-access magnetoelectric (ME) memo...