Chapter 148 Nanoscale rare earth-transition metal multilayers: Magnetic structure and properties

Abstract

Publisher Summary This chapter discusses the magnetic structure, the interfacial magnetism, and the origin of perpendicular magnetic anisotropy (PMA) of lanthanide–transition metal nanoscale multilayers, denoted as “R/T.” In R/T multilayers, the PMA, which is produced by the interaction between 4f electrons of R ions and the electric gradient field of the neighbor ions, is the core of the interfacial magnetism. An additional desirable feature of the lanthanides is that their chemical similarity leads to easy substitution of one for another. The Hund's rule interaction and the presence or absence of orbital angular momentum produces a wide range of ferromagnetic or ferrimagnetic structures when combined with T ions, and either very strong or rather weak magnetic anisotropies. The interactions among all the R and T atoms are the basis for understanding the magnetic properties of multilayers. A brief overview of the magnetic interactions and structures that are important for understanding amorphous R and R–T alloys is presented. The roles that random magnetic anisotropy and exchange interactions play in determining the magnetic structure are emphasized. For the multilayered structure there are many interfaces, each of which is characterized by reduced symmetry in the surrounding atoms, and this feature favors PMA.