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.

The magnetic tape has a magnetic layer and a backcoat layer, wherein the Ra on the magnetic layer side surface is less than or equal to 1.8 nm, the coefficient of friction measured on the base portion of the magnetic layer side surface is less than or equal to 0.35, the Ra measured on the backcoat layer side surface is less than or equal to 5.0 nm, the backcoat layer contains a fatty acid ester, the FWHM.sub.before measured on the backcoat layer side surface before vacuum heating is greater than 0 nm but less than or equal to 10.0 nm, the FWHM.sub.after after vacuum heating is greater than 0 nm but less than or equal to 10.0 nm, and the difference between the spacing measured on the backcoat layer side surface after and before vacuum heating is greater than 0 nm but less than or equal to 8.0 nm.

In a tape recording medium, a sliding layer has an electric resistance of 1×10.sup.8 Ω/sq or less, and contains carbon particles and solid particles. The carbon particles have a primary particle size of 30 nm or less and a BET specific surface area of 100 m.sup.2/g or more. The solid particles have a primary particle size of 100 nm or less, a Mohs' hardness in a range from 2.5 to 8, inclusive, a density of 3 g/cm.sup.3 or more, and a BET specific surface area of 30 m.sup.2/g or more.

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.

The magnetic tape includes a non-magnetic support; a magnetic layer including a ferromagnetic powder and a binding agent on one surface of the non-magnetic support; and a back coating layer including a non-magnetic powder and a binding agent on the other surface of the non-magnetic support, in which a center line average surface roughness Ra measured regarding a surface of the back coating layer is equal to or smaller than 7.0 nm, and a difference between a spacing S.sub.after measured by optical interferometry regarding the surface of the back coating layer after methyl ethyl ketone cleaning and a spacing S.sub.before measured by optical interferometry regarding the surface of the back coating layer before methyl ethyl ketone cleaning is greater than 0 nm and equal to or smaller than 30.0 nm.

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 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.

Provided are a magnetic tape comprising a magnetic layer containing a ferromagnetic powder and a binding agent on a non-magnetic support, in which the magnetic layer contains an oxide abrasive, an average particle diameter of the oxide abrasive obtained from a secondary ion image acquired by irradiating a surface of the magnetic layer with a focused ion beam is 0.04 μm to 0.08 μm, and an absolute value ΔN of a difference between a refractive index Nxy measured with respect to an in-plane direction of the magnetic layer and a refractive index Nz measured with respect to a thickness direction of the magnetic layer is 0.25 to 0.40, and a magnetic recording and reproducing device including the magnetic tape.

The magnetic tape includes: a non-magnetic support; a magnetic layer that includes ferromagnetic powder on one surface side of the non-magnetic support; and a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support, in which the ferromagnetic powder is ferromagnetic powder selected from the group consisting of hexagonal strontium ferrite powder and ε-iron oxide powder, and the number of protrusions having a height of 50 nm or more and less than 75 nm on a surface of the back coating layer is 700 pieces/6400 μm.sup.2 or less.

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.