A magnetic recording medium includes a non-magnetic substrate; a soft magnetic layer; a first seed layer; a second seed layer; an underlayer; and a perpendicular magnetic recording layer. The soft magnetic layer, the first seed layer, the second seed layer, the underlayer and the perpendicular magnetic recording layer are disposed on the non-magnetic substrate in this order. The first seed layer includes MoS.sub.2, hexagonal-BN, WS.sub.2, WSe.sub.2 or graphite. The second seed layer includes AlN having a hexagonal wurtzite type crystal structure. The underlayer includes Ru.

In a magnetic recording medium, an average thickness t.sub.T is t.sub.T5.5 m, a dimensional variation w in a width direction to tension change in a longitudinal direction is 650 ppm/Nw, and a rate of shrinkage in the longitudinal direction is 0.08% or less.

The purpose of the present invention is to provide a perpendicular magnetic recording medium which uses an Ru seed layer having a (002)-oriented hcp structure, and has a magnetic recording layer including a (001)-oriented L1.sub.0 ordered alloy suitable to perpendicular magnetic recording. The magnetic recording medium of the present invention includes a substrate, a first seed layer containing Ru, a second seed layer containing ZnO, a third seed layer containing MgO, and a magnetic recording layer containing an ordered alloy, in this order, the first seed layer having the (002)-oriented hexagonal closest packed structure.

In a magnetic recording medium, an average thickness t.sub.T is t.sub.T5.5 m, a dimensional variation w in a width direction to tension change in a longitudinal direction is 650 ppm/Nw, and a rate of shrinkage in the longitudinal direction is 0.08% or less.

A magnetic recording medium includes a layer structure including a magnetic layer, a non-magnetic layer, and a base layer in this order, in which an average thickness t.sub.T is t.sub.T5.5 m, a dimensional variation w in a width direction to tension change in a longitudinal direction is 660 ppm/Nw, and an average thickness t.sub.n of the non-magnetic layer is t.sub.n1.0 m.

The present disclosure generally relates to a magnetic media drive employing a magnetic recording head. The head includes a main pole at a media facing surface (MFS), a trailing shield at the MFS, and a MAMR stack disposed between the main pole and the trailing shield at the MFS. The MAMR stack includes a seed layer and at least one magnetic layer. The seed layer is fabricated from a thermally conductive material having electrical resistivity lower than that of the main pole. The seed layer has a stripe height greater than a stripe height of the at least one magnetic layer. With the extended seed layer, the bias current from the trailing shield to the main pole spreads further away from the MFS along the extended seed layer before flowing into the main pole, reducing temperature rise at or near the MAMR stack, leading to improved write head reliability.

A magnetic recording cartridge includes a magnetic recording medium of which an average thickness t.sub.T is t.sub.T5.6 m, a dimensional change amount w in a width direction with respect to a tension change in a longitudinal direction is 660 ppm/Nw, and a squareness ratio in a vertical direction is 65% or more, in which the magnetic recording medium is accommodated in a state of being wound around a reel and (a servo track width on an inner side of winding of the magnetic recording medium)(a servo track width on an outer side of winding of the magnetic recording medium)>0 is satisfied.

A magnetic recording cartridge is provided and including a magnetic recording medium, wherein an average thickness of the magnetic recording medium t.sub.T is 3.5 mt.sub.T 5.6 m, a dimensional change amount w in a width direction of the magnetic recording medium with respect to a tension change in a longitudinal direction of the magnetic recording medium is 700 ppm/Nw 20000 ppm, the magnetic recording medium is accommodated in a state of being wound around the reel in the cartridge case and (a servo track width on an inner side of winding of the magnetic recording medium)-(a servo track width on an outer side of winding of the magnetic recording medium) > is satisfied, and a squareness ratio measured in a vertical direction of the magnetic recording medium is 65% or more.

There is provided a magnetic recording medium which has a layer structure including a magnetic layer and a base layer, and of which an average thickness t.sub.T is t.sub.T5.6 m, a dimensional change amount w in a width direction with respect to a change in tension in a longitudinal direction is 660 ppm/Nw, a servo pattern is recorded on the magnetic layer, a standard deviation PES of a position error signal (PES) value obtained from a servo signal in which the servo pattern is reproduced is PES25 nm, and a maximum value .sub.1M of a friction coefficient .sub.1 between a surface on a side of the magnetic layer and an LTO3 head in a case where measurement of the friction coefficient .sub.1 is performed 250 times is 0.04.sub.1M0.5.

There is provided a magnetic recording medium which has a layer structure including a magnetic layer and a base layer, and of which an average thickness t.sub.T is t.sub.T5.6 m, a dimensional change amount w in a width direction with respect to a change in tension in a longitudinal direction is 660 ppm/Nw, a servo pattern is recorded on the magnetic layer, a standard deviation PES of a position error signal (PES) value obtained from a servo signal in which the servo pattern is reproduced is PES25 nm, and a maximum value .sub.1M of a friction coefficient .sub.1 between a surface on a side of the magnetic layer and an LTO3 head in a case where measurement of the friction coefficient .sub.1 is performed 250 times is 0.04.sub.1M0.5.