Title :
Low noise properties and thermal stability of Co-based thin film media for high density longitudinal recording
Author :
Abarra, E.N. ; Okamoto, I. ; Sato, K. ; Yoshida, Y. ; Akimoto, H. ; Uematsu, Y.
Author_Institution :
File Memory Lab., Fujitsu Labs. Ltd., Atsugi, Japan
Abstract :
Media with excellent signal to noise properties and adequate high temperature thermal stability have been developed for over 20 Gbit/in2 recording. The media are fabricated by dc magnetron sputtering onto textured NiP films on Al-Mg substrates. The magnetic layer is a CoCr-based quaternary alloy with (11.0) preferred orientation on a Cr alloy [002] underlayer. The average grain diameter has been reduced to an average of <10 nm. TEM-EDX studies revealed that Cr segregation has been enhanced compared to a previous CoCrPtTa media used for 15 Gbit/in2 recording resulting in improved Co to Cr core composition and increased grain boundary Cr content. Spinstand measurements of the thermal decay after annealing at 65°C indicate sufficient thermal stability at 400 kfci for media with Mrδ>0.3 memu/cm2 consistent with magnetometry measurements.
Keywords :
X-ray chemical analysis; chromium alloys; cobalt alloys; ferromagnetic materials; grain size; hard discs; magnetic recording noise; magnetic thin film devices; sputter deposition; thermal stability; transmission electron microscopy; 65 degC; CoCrPtTa; TEM-EDX studies; core composition; dc magnetron sputtering; grain boundary; grain diameter; high density longitudinal recording; high temperature thermal stability; low noise properties; magnetometry measurements; quaternary alloy; signal to noise properties; spinstand measurements; thermal decay; thin film media; Chromium alloys; Magnetic cores; Magnetic films; Magnetic noise; Magnetic recording; Sputtering; Substrates; Temperature; Thermal stability; Transistors;
Journal_Title :
Magnetics, IEEE Transactions on
