Abstract: A magnetic recording medium is used with a magnetic recording system in which a baseband recording signal is recorded on a magnetic recording medium and a surface-band recording signal with the effective recording depth being smaller than that of the baseband recording signal is then recorded thereon in superimposed relation. The non-magnetic substrate includes thereon a first magnetic layer and a second magnetic layer on that order, said second magnetic layer having a thickness substantially equal to the effective recording depth of said surface-band recording signal and a coercivity higher than that of said first magnetic layer.

Abstract: A magnetic recording medium comprising a substrate and magnetic recording double-layers formed on the substrate, wherein the magnetic material of the magnetic recording under-layer is composed essentially of an alloy or metal magnetic powder having a specific surface area of at most 30 m.sup.2 /g as measured by BET method, and the magnetic material of the magnetic recording top-layer is composed essentially of an iron oxide or Co-adsorbed iron oxide powder having a specific surface area of at least 25 m.sup.2 /g as measured by BET method.

Abstract: A magnetic powder for a magnetic recording medium which is a cobalt-adsorbed magnetic iron oxide having a coercive force of 1000 Oe or more and a ratio of a coercive force at -196.degree. C. to a coercive force at room temperature of 3 or less.

Abstract: A magnetic recording medium comprises a substrate coated with a magnetic composition comprising a cobalt adsorbed iron oxide powder with a phosphoric ester type anionic surfactant at a ratio of 2 wt. % or more and a binder at a ratio of said iron oxide powder to said binder of 4 or more.A magnetic recording medium has a coercive force Hc of 950 to 1200 Oe and a residual magnetic flux .phi..sub.r of 0.35 to 0.6 maxwell.

Abstract: A magnetic recording medium having a magnetic layer comprises a magnetic powder, a binder, a nonionic or anionic surfactant and a silicone oil having a viscosity of 500 c.s. or lower.

Abstract: A magnetic recording medium comprises a magnetic layer formed by coating a magnetic powder composition obtained by mixing an abrasive powder having an average diameter of 0.8 .mu.m or more and an abrasive powder having an average diameter of 0.4 .mu.m or less and a magnetic powder in a binder, on a base film.

Abstract: A magnetic recording medium having a substrate coated with a magnetic layer comprises a binder, a magnetic powder and a metal phosphide at a ratio of 0.2 to 5.0 wt. % based on said magnetic powder.

Abstract: A magnetic coating material for magnetic recording media is produced by dispersing a magnetic coating material containing from 0.1 to 2.0% of an abrasive and from 0.05 to 1.0% of a betaine type ampholytic antistatic agent, both on the basis of the amount of a magnetic powder, in a dispersion mill using steel balls. The abrasive has a hardness of not lower than 6 on Mohs' scale.