First-principles study on magnetic anisotropy of Fe thin films on MgO(001) and Pt(001) for memory storage

Abstract

Magnetic thin films for memory device are one of the field which received most intensive research interests during the last decade. Importance of this system is easily proved in many applications for our daily lives, such as hard drives, galvanic isolators, and magnetic random access memories (MRAM). These magnetic devices are based on the ultrathin layers of alternating ferromagnetic and nonmagnetic (insulator or metal) layers. As the dimensions of the thin films for memory devices shrink down to few atomic layer thicknesses, the importance of interface structure has become more important. Therefore, during the last decade, enormous amount of research efforts have been devoted to clarifying the structure dependent magnetic properties of thin film systems. Many of the works have successfully explained and predicted the structure-property relationship of such system while there still exist many ongoing controversies over such problems. In this thesis, exact pictures of structure dependency of magnetic properties of the Fe-based thin films were drawn using ab initio thermodynamics methods, which connects the conventional thermodynamic formulae and ab initio calculations on system total energies. The main purpose of this thesis is systematic approach to find the most stable defective and alloy structures of Fe/oxide and Fe/metal surface systems find the relationship between the structure and magnetic properties.