1. Field of the Invention
The present invention relates to a magnetic body, a magnetic device using the same, and a method of manufacturing the same.
2. Description of the Related Art
Conventionally, magnetic memory media and magnetic sensors have been produced from magnetic bodies made from magnetic materials such as natural magnets (e.g., magnetite: Fe3O4), alloy magnets (e.g., chrome steel and high cobalt steel), magnets composed of alnico, ferrite and a rare earthes, and more.
Since all of these magnetic materials include magnetic metals, production processes of these magnetic materials, e.g., manufacturing process of a magnetic device on an LSI (Large Scale Integration) substrate using semiconductors such as silicon and gallium arsenate (GaAs), have various issues such as a poor bonding property between adjacent substances.
Therefore, individual circuits have to be formed as separate component parts different from electronic components, such as transistors, formed on the LSI substrate. As the result, a serious obstacle to miniaturization, high integration and reduction in production steps of an electronic circuitry exists.
In the meanwhile, since a semiconductor cluster, a carbon cluster, and a metallic cluster chemically synthesized from non-magnetic materials have no magnetism, mere assemble of these components could not make magnetic materials.
In order to address such an issue, attempts have heretofore been undertaken to fabricate the magnetic body made from non-magnetic materials having flat-band structure. The “flat-band structure” means a band structure with no dependent on a wave number in energy dispersion of electrons. Lieb and Mielke have theoretically shown that materials having the flat-band structure emerge ferromagnetism. The Leib and Mielke theories suggest that charging the electrons into a non-dispersion (that is, a strongly degenerate) system such as the flat-band causes spins of the electrons to be aligned in parallel as much as possible.
In general, when the electrons are filled in a degenerated energy level, the spins are influenced to be oriented in same (parallel) direction as much as possible in order to gain an exchange energy. A typical example of this effect is the Hund first rule in a field of an atomic nucleus model. Their theories show that the same effect is obtained in material having the flat-band structure.
On the basis of their theories, Japanese Patent Application No. 2001-257394 has proposed a magnetic body made from non-magnetic materials such as graphite, gallium (Ga) atoms and arsenate (As) atoms.
This technology contemplates forming quantum dot arrays, placed with a plurality of quantum dots each of which has a periphery formed with a high energy potential region to allow the electrons to be trapped, on particular lattice points used in their theories, such that the electrons are enabled to directly transfer between adjacent quantum dots to realize the flat-band structure to allow ferromagnetism to be generated.
The quantum dot array is an artificially formed crystal, so-called artificial crystal when a quantum dot is regarded as an artificial atom. Due to development of the processing technology in recent years, there has been progressively an increasing capability of manufacturing such an artificial crystal and, in respect of so-called artificial molecules where two quantum dots are bonded, ferromagnetic states with the spins oriented in the same (parallel) direction has been already experimentally realized.