GB1420619A - Magnetic devices - Google Patents

Abstract

1420619 Moving magnetic domain devices WESTERN ELECTRIC CO Inc 21 Dec 1972 [22 Dec 1971] 59020/72 Heading H3B In a single wall magnetic domain device whose domain stability is impaired by temperature changes, the magnetic bias field is arranged to alter with temperature to as to maintain stability. By making the bias field change appropriately the temperature range of the device may be extended to 200‹ C. A construction shown in Fig. 6, has domain material 11 mounted on a sheet held by slots in permanent magnets 53, 54, soft material 51, 52 providing a uniform bias field over the domain material. The initial value of the bias field is governed by the width of air gaps 56, 57 which can be adjusted by screws, Fig. 5 (not shown). The bias may be provided by other means, such as exchange coupled permanent magnet layers on the domain material, it only being necessary to choose a magnet material whose temperature dependency matches that of the domain material. Materials.-The domain materials described are films on non-magnetic substrates, and in the following list each material is given with its substrate; Y 1 . 3 Eu 1 . 7 AlFe 4 O 12 and Gd 3 Ga 5 O 12 ; Lu 1 . 5 Eu 1 . 5 GaFe 4 O 12 and Gd 3 Ga 5 O 12 ; Lu 2 Eu 1 - AlFe 4 O 12 and Y 3 Ga 5 O 12 ; Ca 1 . 5 Bi 1 . 2 V 0 . 9 Fe 4 . 1 O 12 and Gd 3 Sc 1 . 7 Ga 3 . 3 O 12 ; Gd 0 . 5 Y 2 . 4 Yb 0 . 1 AlFe 4 O 12 and Gd 3 Ga 5 O 12 . The permanent magnetic material associated with these materials are BaFe 12 O 19 ; BaAlFe 11 O 19 ; SrFe 14 O 22 ; CeCuFe 0 . 5 - Co 3 . 5 .