Modern electronics has succeeded by controlling the charge degree of freedom of electrons and applying the technologies to devices. In addition to this, spintronics controls the spin degree of freedom of electrons as well and applies the technologies to new devices. Recently, basic research and development of new technologies are now in progress.
The control of the magnetization in ferromagnetic thin films is one of the elemental technologies of spintronics. Ferromagnetic thin films are grown on appropriate substrates by depositing the 3d transition metals such as Fe and Co. The magnetic properties of a film, e.g., the direction of the easy magnetization axis, depend on the atomic species and the structure of the film such as its thickness. Also, the control of the movement of the magnetic domain wall is a promising technology for application to spintronics devices.
Recently electric field control of magnetic properties of ferromagnetic thin films has attracted much attention. This is a promising and ideal method for future magnetic writing technology in spintronics which can realize magnetization switching with low-power consumption. To this end, it is important to study the electric field effects on the structural and electronic properties of the films. In particular, it is indispensable to investigate the electric field effects on the magnetocrystalline anisotropy energy for controlling the magnetization switching.
Magnetoresistive random access memory (MRAM) is a promising device with the following advantages over conventional memories. First, MRAM requires far less memory refreshes and therefore leads to better power consumption. Also, MRAM is speed-competitive with CPU CACHE and amounts to more storage in the mobile devices. Moreover MRAM retains data after a power supply is turned off unlike DRAM. Recently, a new type of MRAM with current-induced domain wall motion has been developed. It has a sufficient thermal stability. From the point of view of the basic research, it is important to study the structural and electronic properties of the magnetic domain wall in detail.