Jian-Tao Wang

Magnetic phase competing in MnAu systems

First-principles total energy calculations on tetragonal MnAu superlattices are performed by means of the self-consistent full-potential linearized augmented-plane-wave method under the generalized gradient approximation. It is shown that the stability of the spin configuration strongly depends on the lattice distortion due to its competitive nature. Using Monte Carlo simulations with exchange parameters deduced from ab initio results, finite-temperature magnetism is also studied and a magnetic phase diagram connected with lattice distortion is obtained.

First-principles study of the magnetic and the electronic properties of Fem/Aun multilayers

Abstract The magnetic properties of Fe m /Au n multilayers are studied by means of the self-consistent full-potential linearized augmented-plane-wave method. It is found that the Fe m /Au n multilayers have enhanced ferromagnetic moment of Fe in all calculated systems. For Fe/Au n with monolayer Fe, it possesses an enhanced moment about 2.8 μ B of Fe, which is almost independent of Au thickness. For Fe m /Au, Fe m /Au m with thick Fe layers the average moment of Fe decreases as the Fe layer thickness increases. These results are discussed in connection with recent experiments and theoretical studies.

First-principles studies on the structural and magnetic properties of (Cr, Mn, Fe)/Ag monatomic multilayers

The structural and magnetic properties of (Cr, Mn, Fe)/Ag monatomic multilayers with the tetragonal ordered structure in paramagnetic, ferromagnetic, and three antiferromagnetic states are studied by means of the self-consistent full-potential linearized augmented-plane-wave method. By means of total-energy minimization, the lattice constants for their ground states are estimated. It is found that ordered Cr/Ag has an AF1-type antiferromagnetic ground state with a large local moment of at the Cr site, ordered Mn/Ag has an AF2-type antiferromagnetic ground state with a large local moment of at the Mn site, and the ordered Fe/Ag monatomic multilayer has a ferromagnetic ground state with an enhanced moment of at the Fe site.

First-principles calculation of the structural and magnetic properties of Fe/Au and Cr/Au monatomic multilayers

The structural and magnetic properties of Fe/Au and Cr/Au monatomic multilayers with the tetragonal ordered structure in paramagnetic, ferromagnetic, and antiferromagnetic states are studied by means of the self-consistent full-potential linearized augmented-plane-wave method. It is found that the ordered Fe/Au monatomic multilayer has a ferromagnetic ground state with an enhanced moment of of Fe. On the other hand, the ordered Cr/Au monatomic multilayer has an antiferromagnetic ground state with a large local moment of Cr. By total energy minimization, the lattice constants for their ground states are determined.

Realization of an effective ultrahigh magnetic field on a nanoscale

In tunnel junctions of which at least one side is a ferromagnet, very large magnetic polarization change (≈0.1µB) and splitting of the spin-up and spin-down Fermi energy (≈0.1 eV) can be created under steady state finite current conditions (bias voltage ≈ 1 volt). This is much higher than can be created by the highest magnetic field on earth. We illustrate this with a specific calculation of a recently observed very large Hall effect in the Al side of a Co-I-Al tunnel junction. Other recent experiments that support this idea are discussed.

Effects of cluster–cluster interactions on the structure and magnetic properties in (Fe6)2

Abstract The structure and magnetic properties of the coupled Fe 6 :Fe 6 cluster have been systematically studied with the density functional formalism, and the Kohn–Sham equation is solved self-consistently with the discrete variational method (DVM). It is found that as the intercluster distance decreases the clusters are deformed, which results in the sensitive changes of magnetic moments. The cluster–cluster coupling energy indicates that the two clusters are weakly coupled, and the HOMO-LUMO gap of the coupled clusters is so small that the two coupled Fe 6 clusters are nearly metallic, and the metal–nonmetal transition can be realized by coupling and decoupling of clusters.