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

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PROBLEM TO BE SOLVED : To provide a magnetic powder which is scattered well in a resin coating even if the magnetic powder comprises nanoparticulates having a diameter of less than 80 nm, in some cases, less than 50 nm when the magnetic power is turned into the form of a coating to form a magnetic layer for a magnetic recording medium, and which has an excellent storing stability while maintaining excellent magnetic characteristics. SOLUTION : The magnetic powder is mainly made of Fe which is surface-treated with a silane coupling agent, and contains Co of 20-50 at.% in terms of atomic percentage of Co/Fe, Al of 5-30 at.% in terms of atomic percentage of Al/Fe, and one or two or more kinds of rare earth elements R (including Y) of 4-20 at.% in terms of atomic percentage of R/Fe. The average grain diameter is less than 80 nm, a TAP density is 0.7g/cm3 or above, an ignition point is 165°C or above, and an oxygen content is 26 wt.% or less.