1991/07/01 by Eckart Kneller, Reinhard Hawig · 2 citations
Materials Science · Physics and Astronomy · #Magnetic Properties of Alloys #Magnetic properties of thin films #Hydrogen Storage and Materials #Magnet #Coercivity #Remanence #Ferromagnetism #Demagnetizing field #Condensed matter physics #Isotropy #Materials science #Metastability #Phase (matter) #Magnetic field #Nuclear magnetic resonance #Physics #Magnetization #Quantum mechanics
paper · doi:10.1109/20.102931
openalex publication_date 1991/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
It is proposed that permanent magnets can be made of composite materials consisting of two suitably dispersed ferromagnetic and mutually exchange-coupled phases, one of which is hard magnetic in order to provide a high coercive field, while the other may be soft magnetic, just providing a high saturation J/sub s/, and should envelop the hard phase regions in order to prevent their corrosion. A general theoretical treatment of such systems shows that one may expect, besides a high energy product (BH)/sub max/, a reversible demagnetization curve (exchange-spring) and, in certain cases, an unusually high isotropic remanence ratio B/sub r//J/sub s/, while the required volume fraction of the hard phase may be very low, on the order of 10%. The technological realization of such materials is shown to be based on the principle that all phases involved must emerge from a common metastable matrix phase in order to be crystallographically coherent and consequently magnetically exchange coupled.>