Abstract: A magnetic recording medium which comprises a substrate and a magnetic layer comprising hexagonal system ferrite powder of the formula:AO.multidot.n{[Fe.sub.1-(x+y) .multidot.M.sup.2+.sub.x .multidot.M.sup.4+.sub.y ].sub.2 O.sub.3 } (I)wherein,A is at least one metal selected from the group consisting of Ba, Sr, Pb and Ca,M.sup.2+ is at least one divalent metal ion selected from the group consisting of Mn, Co, Ni, Cu, Zn and Mg,M.sup.4+ is at least one tetravalent metal ion selected from the group consisting of Ti, Zr, Sn, Ge, V and Nb,n is a number of 3 to 8,x and y are such numbers that x+y is from 0.02 to 0.3 and x/y is from 0.2 to 0.8.,and which has a temperature dependency such that the coercive force of the magnetic layer is at a minimum in the temperature range of -20.degree. to 50.degree. C. and has a higher coercive force outside said temperature rangehas good storage property.

Abstract: A magnetic recording medium suitable for high density recording comprising a substrate and a magnetic layer wherein the magnetic layer comprises a binder resin and ferrite magnetic powder comprising hexagonal system plate particles having such magnetic anisotropy that a magnetic anisotropy constant K.sub.1 corresponding to the vertical magnetic component and a magnetic anisotropy constant K.sub.2 corresponding to the horizontal magnetic component, both derived from Fourier analysis of a magnetic torque curve measured in a plane including the C axis of the hexagonal system, satisfy following equations:0.5<K.sub.1 /K.sub.2 <5 and K.sub.1 >0,The magnetic recording medium is suitable for use in high density recording.

Abstract: Magnetic recording medium comprising a magnetic layer formed by magnetic powder including acicular magnetic powder with the magnetic anisotropy to be oriented perpendicular to the acicular direction which is oriented in parallel with the magnetic layer.

Abstract: In a magnetic recording medium, double magnetic layers are formed on one side of a substrate with a lower magnetic layer containing metallic magnetic particles formed on the substrate and an upper magnetic layer containing plate-shaped ferrite magnetic particles of the hexagonal structure with the magnetization axis oriented in a direction vertical to the surface of the upper magnetic layer formed on the lower magnetic layer for enabling high output level recording over a wide wave length range.

Abstract: A method for the production of uniform acicular metal magnetic particles comprising predominantly iron which have excellent magnetic characteristics and are useful as a recording element for a magnetic recording medium, said method comprising the steps of coating the surface of metal compound particles containing predominantly acicular iron oxyhydroxide or iron oxides with at least one member selected from the group consisting of an aluminum compound and a silicon compound, pelletizing the coated particles, and reducing the pellets with heating under reducing atmosphere, e.g. under hydrogen stream.