### 4.4.3 Summary to: Technical Materials and Applications

| Uses of ferromagnetic materials may be sorted according to: |  |
|  | Soft magnets; e.g. Fe - alloys |  |
Everything profiting from an "iron core": Transformers, Motors, Inductances, ... Shielding magnetic fields.
|  | Hard magnets; e.g. metal oxides or "strange" compounds. |  |
Permanent magnets for loudspeakers, sensors, ... Data storage (Magnetic tape, Magnetic disc drives, ...
| Even so we have essentially only Fe, Ni and Co (+ Cr, O and Mn in compounds) to work with, innumerable magnetic materials with optimized properties have been developed. |  |
Strongest permanent magnets: Sm2Co17 Nd2Fe14B
|  | New complex materials (including "nano"materials) are needed and developed all the time. |
| Data storage provides a large impetus to magnetic material development and to employing new effects like "GMR"; giant magneto resistance; a purely quantum mechanical effect. |  |

© H. Föll (Electronic Materials - Script)