Magnetization Profile in the d=2 Semi-Infinite Ising Model and Crossover between Ordinary and Normal Transition

We theoretically investigate the spatial dependence of the order parameter of the two-dimensional semi-infinite Ising model with a free surface at or above the bulk critical temperature. Special attention is paid to the influence of a surface magnetic field $h_1$ and the crossover between the fixed points at h_1=0 and h_1=infinity. The sharp increase of the magnetization m(z) close to the boundary generated by a small h_1, which was found previously by the present authors in the three-dimensional model, is also seen in two dimensions. There, however, the universal short-distance power law is modified by a logarithm. By means of a phenomenological scaling analysis, the short-distance behavior can be related to the logarithmic dependence of the surface magnetization on h_1. Our results, which are corroborated by Monte Carlo simulations, provide a deeper understanding of the existing exact results concerning the local magnetization and relate the short-distance phenomena in two dimensions to those in higher dimensionality.Comment: 20 pages, 9 figures, submitted to Phys. Rev.

Marina El-Alamein Polish-Egyptian conservation mission : research and conservation in the 2011 season

In 2011, the program of the Polish-Egyptian Conservation Mission to Marina el-Alamein included research and conservation in the public quarter of the ancient town, at the necropolis and in a few houses. The mission focused on the anastylosis of the superstructure of a large tomb (T17), and continued work in the area south of the Forum, where remains of Roman public baths from the 2nd to the 4th century AD have survived. Current maintenance and conservation work was carried out as usual in some of the ancient Roman houses in the eastern part of the site

Ab initio studies of the tunneling magneto-Seebeck effect: influence of magnetic material

We found a strong influence of the composition of the magnetic material on the temperature dependence of the tunneling magneto-Seebeck effect in $MgO$ based tunnel junctions. We use \textit{ab initio} alloy theory to consider different $Fe_xCo_{1-x}$ alloys for the ferromagnetic layer. Even a small change of the composition leads to strong changes in the magnitude or even in the sign of the tunneling magneto-Seebeck effect. This can explain differences between recent experimental results. In addition, changing the barrier thickness from six to ten monolayers of $MgO$ leads also to a non-trivial change of the temperature dependence. Our results emphasize that the tunneling magneto-Seebeck effect depends very crucially and is very sensitive to material parameters and show that further experimental and theoretical investigations are necessary

Tailoring magnetoresistance through rotating Ni particles

We present \textit{ab initio} studies for different Ni nanocontacts and show changes in the conductance of such constrictions due to atomic rearrangements in the contact. In particular we consider a Ni particle and show that the magnetoresistance can change from a few to 50% and can even reverse sign as a function of the contact area formed between the particle and the leads.Comment: 10 pages, 4 figures, 7 tables; corrected typos in reference