Longitudinal magnetic media having a granular magnetic layer
View Patent ↗A novel method of manufacturing a longitudinal granular oxide recording medium is disclosed. The method preferably entails obtaining a non-magnetic substrate, heating the substrate at a temperature T 1 that is greater than 150° C., forming a first layer with body-centered cubic atomic structure and with a <200> preferred growth orientation, cooling the substrate to a temperature T 2 and forming a second layer comprising a magnetic oxide-containing granular magnetic layer with a hexagonal close packed atomic structure and with a <11-20> preferred growth orientation. The magnetic oxide-containing granular magnetic layer contains magnetic crystal grains that are substantially isolated by an inter-granular region comprising a non-magnetic substance, wherein the non-magnetic substance is preferably an oxide-containing material.
1. A longitudinal granular oxide recording medium, comprising:
(a) at least one non-magnetic layer with body-centered cubic atomic structure with a (200) preferred growth orientation,
(b) at least one interlayer with hexagonal close packed atomic structure and with a <11-20> preferred growth orientation,
(c) at least one magnetic oxide-containing granular magnetic layer with hexagonal close packed atomic structure and with a <11-20> preferred growth orientation
wherein the interlayer comprises at least two layers: a first interlayer, IL 1 , located above first layer (a) and comprising a Co—X alloy, wherein X is selected from the group consisting of Cr, Pt, Ta, B, W, Mo, Ru, Si, Cu, Ag, Ge, Nb, Fe, Ni, Au and combinations thereof, and a second interlayer, IL 2 , comprising a Ru—Y alloy, wherein Y is selected from the group consisting of Rh, Ir, Cr, Re, Co, V, W, Ta, Zr, Hf, Ti, Mo, Au and combinations thereof.
2. The longitudinal granular oxide recording medium of claim 1 , wherein the first interlayer comprises at least 50 at. % of Co and the second interlayer comprises at least 50 at. % of Ru.
3. The longitudinal granular oxide recording medium of claim 1 , wherein the magnetic oxide-containing granular magnetic layer comprises magnetic crystal grains that are substantially isolated by an inter-granular region comprising a non-magnetic substance.
4. The longitudinal granular oxide recording medium of claim 3 , wherein there is substantially no diffusion of the non-magnetic substance from the magnetic crystal grains to the inter-granular region.
5. The longitudinal granular oxide recording medium of claim 1 , further comprising a substrate having a textured surface and the magnetic oxide-containing granular magnetic layer has an OR-Mrt of greater than 1.0.
6. The longitudinal granular oxide recording medium of claim 1 , wherein a full-width at half-maximum of a rocking curve of the magnetic oxide-containing granular magnetic layer in a [11-20] direction is less than 10°.
7. The longitudinal granular oxide recording medium of claim 1 , wherein a full-width at half-maximum of a rocking curve of the magnetic oxide-containing granular magnetic layer in a [11-20] direction is less than 7° and the magnetic oxide-containing granular magnetic layer has an OR-Mrt of greater than 1.4.