Patent GB-1318010-A (GB)
Title: Magnetoelectronic semiconductor arrangements
IPC: C22C28/00
Filed: 1971-12-17
Abstract: 1318010 Magnetoelectronic solid state devices SIEMENS AG 17 Dec 1971 [30 Dec 1970] 58833/71 Heading H1K A solid state magnetoelectronic device comprises, in a single body, at least one semiconductor region 12 and at least one magnetic region 11 comprising a rare earth silicide or germanide. The silicides are stated to be ferromagnetic while the germanides are antiferromagnetic. Examples of suitable magnetic materials are RE 5 Si 4  and RE 5 Ge 4  (RE=Gd, Tb, Dy, Ho or Er), Gd 5 Si 4-x  (O<x<4), RE<SP>1</SP> 5 Si 3  and RE<SP>1</SP> 5 Ge 3  (RE<SP>1</SP>=Nd, Dy or Gd), Nd 5 Si 1À5 - Ge 1À5 , Gd 5 Si 2 Ge, Gd 5 Si 1À5 Ge 1À5  and Gd 5 SiGe 2 , the material being either doped or undoped, and electrically conducting or insulating, according to the particular application. Semi-conductor materials referred to are Si, Ge, and III-V or II-VI compounds or combinations thereof. A wide variety of configurations is disclosed, involving in some cases two or more magnetic and semi-conductor regions and including structures containing further magnetic regions made of ferrites. Applications.-In a first group of applications the electrical properties of the semi-conductor region are influenced by the magnetic properties of the rare earth silicide or germanide. For example, the temperature dependence of magnetic susceptibility of the rare earth silicide or germanide, particularly in the vicinity of the Curie temperature or the NÚel temperature, may result in a temperature-induced switching effect in the semi-conductor. Alternatively the transport properties of the semi-conductor may be altered by changes induced in the magnetic field of the magnetic material by an electrical current, e.g. a photo-current, therein. In a further application of the first group the magnetization of the rare earth silicide or germanide, and hence the transport properties of the semiconductor, is controlled by an externally applied magnetic field or by a magnetic field associated with another magnetic region in the same body. A second group of applications involves the influence of electrical processes in the semiconductor upon the magnetic properties of the rare earth silicide or germanide. This may involve the switching of magnetic states by plasma effects in an adjacent semi-conductor, e.g. by quantum mechanical tunnelling-through of a thin silicide film by hot electrons from semicondutor material surrounding the silicide. Spin waves may also be energized in the magnetic material by hot electrons from plasma oscillations in the semi-conductor, e.g. produced optically. The spin state configuration may then be interrogated magnetically. In modifications pulses of magnetic flux control conversion of optical data into electrical signals or magnetically stored data is interrogated by photocurrent pulses. A third group of applications entail mutual reactions of plasma processes in semi-conductors with magnetic states in rare earth silicides or germanides, and includes the use of alternating magnetic/semi-conductor multilayer structures which are highly anisotropic with respect to electron transport and electromagnetic effects. Electroluminescent and laser devices are also referred to, e.g. in which an optical output is modulated with magnetically stored information.