J.-G.Ha

First-Principles Calculation of the Magnetic Anisotropy Energies of Ag/Fe(001) and Au/Fe(001) Multilayers

The anisotropy energies of (111) and (001) oriented Ag/Fe and Au/Fe multilayers are obtained by a first-principle calculation to investigate the orientational dependence of the magnetic anisotropy. All systems show perpendicular anisotropy in good agreement with experiments. In the case of Ag/Fe multilayers, the anisotorpy energy of the (001) oriented multilayer is larger than that of the (111) multilayer. In contrast to Ag/Fe, Au/Fe(111) multilayer exhibits a stronger perpendicular anisotropy than the (001) oriented system. In all systems, a large minority-spin LDOS of | m | =2 character of Fe near the Fermi energy could be the origin of perpendicular magnetic anisotropy.

Theoretical study on the strain dependence of the magnetic anisotropy of X/Co(X=Pt, Cu, Ag, and Au) metallic multilayers

A first‐principles calculation of the magnetic anisotropy energies of X/Co (X=Pt, Cu, Ag and Au) metallic multilayers has been performed to investigate the effect of strain on the magnetic anisotropy. It is successfully predicted that Pt/Co and Au/Co multilayers exhibit perpendicular magnetic anisotropies in accordance with experiments. The strength of the hybridization of electronic states at the interface determines the relative position of the Fermi energy to the local density of states (LDOS) of ‖m‖=2 character of Co d electrons of minority spin. If the LDOS of ‖m‖=2 character is large at the Fermi energy, a system shows a perpendicular anisotropy. The anisotropy energies of all the systems increase as a function of interatomic distance in the in‐plane direction. The magneto‐elastic constants are more than twice the value of pure Co. The origin of this large value is explained in terms of the change of relative position of the Fermi level to that of the LDOS of ‖m‖=2 character as the value of strain i...

Magnetic anisotropy and magneto-optical Kerr effect of metallic multilayers

We prepared multilayers on glass substrates by RF magnetron sputtering at room temperature. multilayers exhibit a magnetic easy axis perpendicular to the film plane up to a larger magnetic layer thickness than do Co/Pd multilayers. In particular, multilayers became perpendicular at 33 A. The magnetic anisotropy can be explained by the strain effect. The role of the magnetoelastic energy due to the in-plane strain in the system is pointed out and discussed. We also investigated the magneto-optical polar Kerr effect of these multilayers. The polar Kerr rotation angle increases when the Au concentration is 4.5 at.% compared to Co/Pd multilayers but decreases with increasing Au content.

Perpendicular Magnetic Anisotropy of Metallic Multilayers Composed of Magnetic Layers Only: Ni/Co and Ni/Fe Multilayers

The magnetic anisotropy energies of multilayers which include only magnetic elements, Ni/Co and Ni/Fe, are calculated from first principles. Both systems show perpendicular anisotropy but the anisotropy energy is somewhat smaller than that of well-studied systems such as Pd/Co. The LDOS (local density of states) of Ni is as large as that of Co(Fe) at the Fermi level and contributes directly to perpendicular anisotropy, which means that the magnetic moments of Ni are also normal to the film plane. The anisotropy cannot be explained only in terms of the electronic structure of Co(Fe) near the Fermi level but that of Ni must also be considered. The origin of the perpendicular anisotropy is attributed to a large LDOS of |m| =2 character of Co(Fe) and Ni minority spin near the Fermi energy.

The effect of crystal orientation on the magnetic anisotropy of Pd/Co metallic multilayers

First-principles calculations of the magnetic anisotropy energies of Pd/Co(111) and Pd/Co(001) metallic multilayers have been performed to investigate the orientational dependence of the magnetic anisotropy. The calculated results indicate perpendicular magnetic anisotropy for both systems in accordance with experiments, and the anisotropy energy of the (111) oriented multilayer is more than four times larger than that of the (001) multilayer. The perpendicular magnetic anisotropies of these systems are explained by the same electronic origin, a large LDOS of |m| =2 character of Co minority spin near the Fermi energy. The small anisotropy of the (001) multilayer can be attributed to the weaker hybridization at the interface as compared to the case of the (111) system.

Theoretical study on the Co layer thickness dependence of the magnetic anisotropy of Pd/Co multilayers

Abstract The magnetocrystalline anisotropy energies of Pd(3ML)/Co(xML) (ML: monolayer) (x= 1, 2, 3, 4, 5, and 6) multilayers have been calculated from first principles within the local-spin-density approximation using the linear muffin-tin orbital (LMTO) method including spin-orbit coupling. The easy axes are found to be perpendicular to the film plane, which is in good agreement with experiments. The anisotropies of orbital angular momentum of the Co atoms near the interface are larger than those of the Co atoms away from the interface. This fact indicates that the contribution to perpendicular anisotropy is larger for the Co atoms near the interface rather than those located distant from the interface and confirms the existence of interface anisotropy.

Perpendicular magnetic anisotropy and magnetooptical properties of (Co/sub 1-x/Ni/sub x/)/Pd multilayers

The magnetic and magnetooptical properties of (Co/sub 1-x/Ni/sub x/)/Pd multilayers were systematically investigated. The addition of Ni to the Co layer simultaneously decreases the Curie temperature and Kerr rotation angle, but the decrease of the Curie temperature is larger. By controlling the Ni content it is possible to reduce the Curie temperature. The perpendicular magnetic anisotropy energy also decreases with the addition of Ni, but the change is small. The interfacial anisotropy energy and volume anisotropy energy were calculated and discussed. Adding Ni to the Co layer can yield control of magnetic and magnetooptical properties, while maintaining a large effective perpendicular anisotropy energy.