EarthRef.org Reference Database (ERR) -- Ambatiello & Soffel 1996

Magnetic domain structure observations have been carried out on small synthetic. Ti-rich titanomagnetite (TM) grains (ulv¿spinel content 50%--70%) employing the magneto-optical Kerr effect (MOKE). On randomly oriented grains simple domain structures with planar domains or complex domain structures with curved domains and reverse spike domains have been observed. In addition to the description of the domain pattern, a qualitative determination of the magnetization direction within the domains is presented. Planes with a magnetization parallel to the surface show broad domains with nearly straight domain walls while planes with a magnetization normal to the surface show narrow domains and more complex patterns. With the help of the observed domain patterns on the randomly oriented grains and the knowledge about the magnetization direction within the domains a three-dimensional (3-D) domain structure model for Ti-rich TM is proposed. These Ti-rich titanomagnetites have only one easy direction of the magnetization and show a real uniaxial character, although the magnetic mineral is cubic. By analyzing the domain structure of more than a hundred TM particles in a range of size between 1.7 and 20 microns the transition from the single-domain (SD), to the multi-domain (MD) state is determined. The fit of the data in this study gives a critical SD size of ≈1.1 &mgr;m for Ti-rich TM. ¿ American Geophysical Union 1996 Magnetic domain structure observations have been carried out on small synthetic. Ti-rich titanomagnetite (TM) grains (ulv¿spinel content 50%--70%) employing the magneto-optical Kerr effect (MOKE). On randomly oriented grains simple domain structures with planar domains or complex domain structures with curved domains and reverse spike domains have been observed. In addition to the description of the domain pattern, a qualitative determination of the magnetization direction within the domains is presented. Planes with a magnetization parallel to the surface show broad domains with nearly straight domain walls while planes with a magnetization normal to the surface show narrow domains and more complex patterns. With the help of the observed domain patterns on the randomly oriented grains and the knowledge about the magnetization direction within the domains a three-dimensional (3-D) domain structure model for Ti-rich TM is proposed. These Ti-rich titanomagnetites have only one easy direction of the magnetization and show a real uniaxial character, although the magnetic mineral is cubic. By analyzing the domain structure of more than a hundred TM particles in a range of size between 1.7 and 20 microns the transition from the single-domain (SD), to the multi-domain (MD) state is determined. The fit of the data in this study gives a critical SD size of ≈1.1 &mgr;m for Ti-rich TM. ¿ American Geophysical Union 1996