The magnetic tape includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which the magnetic layer has a servo pattern, and an absolute value N of a difference between a refractive index Nxy measured regarding an in-plane direction of the magnetic layer and a refractive index Nz measured regarding a thickness direction of the magnetic layer is 0.25 to 0.40, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape.

The magnetic tape includes a non-magnetic support; a magnetic layer including ferromagnetic powder and a binding agent on one surface side of the non-magnetic support; and a back coating layer including non-magnetic powder and a binding agent on the other surface side of the non-magnetic support, in which an isoelectric point of a surface zeta potential of the magnetic layer is equal to or smaller than 3.8, and an isoelectric point of a surface zeta potential of the back coating layer is equal to or smaller than 3.0, a magnetic tape cartridge, and a magnetic tape apparatus including this magnetic tape.

The magnetic tape includes: a non-magnetic support; and a magnetic layer containing a ferromagnetic powder, in which a contact angle with 1-bromonaphthalene, which is measured on a surface of the magnetic layer, is 45.0? or more and 55.0? or less, and standard deviation ? of the contact angle in a width direction of the surface of the magnetic layer is 1.0? or less.

The magnetic tape includes: a non-magnetic support; and a magnetic layer containing a ferromagnetic powder, in which the number of recesses existing on a surface of the magnetic layer and having an equivalent circle diameter of 0.25 ?m or more and 0.55 ?m or less is 10 or more and 500 or less per an area of 40 ?m?40 ?m, and standard deviation a of the number of the recesses in a width direction of the surface of the magnetic layer is 50 or less.

An aspect of the present invention relates to a composition, which is a composition for a magnetic recording medium and comprises an isocyanate compound in the form of an adduct of a polyhydroxyl compound having one or more aromatic carbon rings and three or more hydroxyl groups per molecule with a polyisocyanate having two or more isocyanate groups per molecule.

The metal oxide particle dispersion for manufacturing a particulate magnetic recording medium contains metal oxide particles, solvent, and a polyester compound having one or more groups selected from the group consisting of a carboxyl group and a salt thereof, a phosphoric acid group and a salt thereof, a hydroxyl group and a nitrogen-substituted alkylene group, but substantially not containing ferromagnetic powder.

The magnetic tape includes: a non-magnetic support; and a magnetic layer containing a ferromagnetic powder, in which the number of recesses existing on a surface of the magnetic layer and having an equivalent circle diameter of 0.25 m or more and 0.55 m or less is 10 or more and 500 or less per an area of 40 m40 m, and standard deviation a of the number of the recesses in a width direction of the surface of the magnetic layer is 50 or less.

The magnetic tape includes: a non-magnetic support; and a magnetic layer containing a ferromagnetic powder, in which a contact angle with 1-bromonaphthalene, which is measured on a surface of the magnetic layer, is 45.0 or more and 55.0 or less, and standard deviation of the contact angle in a width direction of the surface of the magnetic layer is 1.0 or less.