MAGNETIC POWDER AND MAGNETIC RECORDING MEDIUM USING THE SAME, AND METHOD FOR SURFACE TREATMENT OF M

A magnetic powder containing Fe as a primary component and being surface-treated with a silane coupling agent, characterized in that it comprises Co in an atomic percentage of Co/Fe of 20 to 50 at. %, Al in an atomic percentage of Al/Fe of 5 to 30 at. %, and one or more of rare earth elements R (including Y) in an atomic percentage of R/Fe of 4 to 20 at. %, and has an average particle diameter of less than 80 nm, a TAP density of 0.7 g/cm3 or more, an ignition temperature of 165˚C or higher, an oxygen content of 26 wt % or less.