Computers of higher capacities of increased efficiency at reasonable costs are essential for handling and processing huge data. Researchers from German-French research team have succeeded in this direction. This has been done by combining the concepts of spin electronics and molecular electronics in a single component consisting of a single molecule.
Magneto resistance
Magneto resistance is the property of a material to change the value of its electrical resistance when an external magnetic field is applied to it. The property of magneto resistance is used in reading the bits on magnetic tape and disk. The physical origin of the magneto resistance effect lies in spin orbit coupling. The electron cloud about each nucleus deforms slightly as the direction of the magnetization rotates, and this deformation changes the amount of scattering undergone by the conduction electrons when traversing the lattice.
The ferromagnetic material utilized for Anisotropic Magneto Resistance (AMR) heads is NiFe (permalloy). This is because of the relatively large effect at room temperature and the low saturation fields required for obtaining the AMR effect. In recording heads, the geometry is such that the field from the media is transverse to the current direction in the head.
Giant Magneto resistance
Giant magneto resistance (GMR) occurs in structures containing ferromagnetic contacts separated by a metallic non-magnetic spacer, and is now the basis of read heads for hard drives and for new forms of random access memory. Such components allow for the production of very small and highly efficient magnetic field sensors for read heads in hard disks or for non-volatile memories in order to further increase reading speed and data density.
Very weak magnetic changes give rise to major differences in electrical resistance in a GMR system. A system of this kind is the perfect tool for reading data from hard disks when information registered magnetically has to be converted to electric current. Even the most recent read-out techniques of today are further developments of GMR and are considered as one of the first real applications of the promising field of nanotechnology.
Spin electronics
In spin electronics, the information is encoded in the intrinsic spin rotation of the electron. This spin is maintained even when switching off current supply, which means that the component can store information without any energy consumption.