A hexagonal strontium ferrite powder, in which an average particle size is 10.0 to 25.0 nm, a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, and a coercivity Hc is greater than 2,000 Oe and smaller than 4.000 Oe. A magnetic recording medium including: a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which the ferromagnetic powder is the hexagonal strontium ferrite powder. A magnetic recording and reproducing apparatus including this magnetic recording medium.

An object is to provide a magnetic recording medium having excellent traveling stability and a thin total thickness. The present technology provides a tape-shaped magnetic recording medium including: a magnetic layer; an underlayer; a base layer; and a back layer, in which a surface on a side of the magnetic layer has a kurtosis of 3.0 or more, a surface on a side of the back layer has a kurtosis of 2.0 or more, the surface on the magnetic layer side has arithmetic average roughness R.sub.a of 2.5 nm or less, the base layer includes a polyester as a main component, the magnetic recording medium has an average thickness t.sub.T of 5.6 μm or less, the magnetic recording medium includes a lubricant, the lubricant includes a fatty acid and a fatty acid ester, and a mass ratio between the fatty acid and the fatty acid ester extracted with hexane satisfies fatty acid/fatty acid ester≤0.6, and the magnetic recording medium has pores, and the pores have an average diameter of 6 nm or more and 11 nm or less when the diameters of the pores are measured in a state where the lubricant has been removed from the magnetic recording medium and the magnetic recording medium has been dried.

A magnetic recording medium is a magnetic recording medium in the form of a tape and includes a substrate, a foundation layer provided on the substrate, and a magnetic layer provided on the foundation layer and containing a magnetic powder. The foundation layer and the magnetic layer each contain a lubricant. A squareness ratio of the magnetic layer in a perpendicular direction is equal to or higher than 65%, an average thickness of the magnetic recording medium is equal to or smaller than 5.6 μm, a plurality of recessed portions each having a depth corresponding to 20% or higher of the average thickness of the magnetic layer is provided on a surface of the magnetic layer, and the number of the recessed portions per unit area of 1,600 μm.sup.2 of the surface of the magnetic layer is equal to or greater than 20 and equal to or smaller than 200, and an amount of exudation of the lubricant per unit region of 12.5 μm×9.3 μm on the surface of the magnetic layer in a vacuum is equal to or greater than 3.0 μm.sup.2 and equal to or smaller than 6.5 μm.sup.2.

An object of the present disclosure is to provide a magnetic recording medium excellent in electro-magnetic conversion characteristic and thermal stability.

The present disclosure provides a tape-shaped magnetic recording medium including: a substrate; and a magnetic layer provided over the substrate and including a magnetic powder, in which the magnetic layer has an average thickness of equal to or less than 90 nm, the magnetic powder has an average aspect ratio of from 1.0 to 3.0, the magnetic powder has an average particle volume of equal to or less than 2,300 nm.sup.3, a coercive force Hc1 in a vertical direction of the magnetic recording medium is equal to or less than 4,500 Oe, a coercive force Hc2 in a longitudinal direction of the magnetic recording medium and the coercive force Hc1 satisfy a relation of Hc2/Hc1≤0.8, and the ratio Hrp/Hc1 of a residual coercive force Hrp of the magnetic recording medium measured using a pulsed magnetic field and the coercive force Hc1 is equal to or less than 2.0.

An object of the present disclosure is to provide a magnetic recording medium excellent in electro-magnetic conversion characteristic and thermal stability. The present disclosure provides a tape-shaped magnetic recording medium including: a substrate; and a magnetic layer provided over the substrate and including a magnetic powder, in which the magnetic layer has an average thickness of equal to or less than 90 nm, the magnetic powder has an average aspect ratio of from 1.0 to 3.0, the magnetic powder has an average particle volume of equal to or less than 2,300 nm.sup.3, a coercive force Hc1 in a vertical direction of the magnetic recording medium is equal to or less than 4,500 Oe, a coercive force Hc2 in a longitudinal direction of the magnetic recording medium and the coercive force Hc1 satisfy a relation of Hc2/Hc1≤0.8, and the ratio Hrp/Hc1 of a residual coercive force Hrp of the magnetic recording medium measured using a pulsed magnetic field and the coercive force Hc1 is equal to or less than 2.0.

The present technology provides a tape-shaped magnetic recording medium including: a magnetic layer; an underlayer; a base layer; and a back layer, in which the number of recesses having a depth of 20% or more of the thickness of the magnetic layer is 10 or more and 200 or less per surface area of 1600 μm.sup.2, the base layer includes a polyester as a main component, a surface on a side of the back layer has a kurtosis of 2.0 or more and 4.4 or less, the magnetic recording medium has an average thickness t.sub.T of 5.6 μm or less, the magnetic recording medium includes a lubricant, the magnetic recording medium has pores, and the pores have an average diameter of 6 nm or more and 11 nm or less when the diameters of the pores are measured in a state where the lubricant has been removed from the magnetic recording medium and the magnetic recording medium has been dried.

The magnetic tape includes a non-magnetic support and a magnetic layer including ferromagnetic powder and a binding agent, in which the magnetic layer has a timing-based servo pattern, an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference (L.sub.99.9−L.sub.0.1) between a value L.sub.99.9 of a cumulative distribution function of 99.9% and a value L.sub.0.1 of a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and an isoelectric point of a surface zeta potential of the magnetic layer is 3.8 or less.

A magnetic recording medium is a magnetic recording medium in the form of a tape and includes a substrate, a foundation layer provided on the substrate, and a magnetic layer provided on the foundation layer and containing a magnetic powder. The foundation layer and the magnetic layer each contain a lubricant. A squareness ratio of the magnetic layer in a perpendicular direction is equal to or higher than 65%, an average thickness of the magnetic recording medium is equal to or smaller than 5.6 μm, a plurality of recessed portions each having a depth corresponding to 20% or higher of the average thickness of the magnetic layer is provided on a surface of the magnetic layer, and the number of the recessed portions per unit area of 1,600 μm.sup.2 of the surface of the magnetic layer is equal to or greater than 20 and equal to or smaller than 200, and an amount of exudation of the lubricant per unit region of 12.5 μm×9.3 μm on the surface of the magnetic layer in a vacuum is equal to or greater than 3.0 μm.sup.2 and equal to or smaller than 6.5 μm.sup.2.

A magnetic recording medium includes: a substrate that is long in shape; and a magnetic layer containing magnetic powder and a binder. The glass transition point of the binder is not lower than 75° C. In a case where atomic force microscope observation images in a 10 μm×10 μm rectangular shape are acquired at five locations randomly selected from the surface on the side of the magnetic layer, any linear protrusion that is 3 nm to 20 nm in height, is 0.3 μm to 1.0 μm in width, and extends across two sides of the observation image does not exist in the observation images of four locations among the acquired observation images of the five locations.

The magnetic recording medium includes a non-magnetic support; a magnetic layer including a ferromagnetic powder on one surface of the non-magnetic support; and a back coating layer including a non-magnetic powder on the other surface of the non-magnetic support, in which a difference (S.sub.after−S.sub.before) between a spacing S.sub.after measured by optical interferometry regarding a surface of the back coating layer after ethanol cleaning and a spacing S.sub.before measured by optical interferometry regarding the surface of the back coating layer before ethanol cleaning is greater than 0 nm and equal to or smaller than 15.0 nm, and the non-magnetic support is an aromatic polyester support having a moisture absorption of 0.3% or less.