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.

A magnetic recording medium is provided and includes a magnetic layer, a non-magnetic layer, a base layer and a back layer, wherein an average thickness t.sub.T of the magnetic recording medium is t.sub.T5.3 m, a dimensional change amount w in a width direction with respect to a change in tension in a longitudinal direction is 700 ppm/Nw, a thickness of the non-magnetic layer is 2.0 m or less, a squareness ratio measured in a vertical direction of the magnetic recording medium is 65% or more, and the magnetic layer includes a magnetic powder.

A tape-shaped magnetic recording medium includes a base, a nonmagnetic layer that is provided on the base and contains a nonmagnetic powder, and a magnetic layer that is provided on the nonmagnetic layer and contains a magnetic powder. In the magnetic recording medium, the magnetic layer has an average thickness of not more than 90 nm, the magnetic powder has an average aspect ratio of from 1.0 to 3.0, a coercive force Hc1 in a perpendicular direction is not more than 3,000 Oe, the coercive force Hc1 in the perpendicular direction and a coercive force Hc2 in a longitudinal direction satisfy the relation of Hc2/Hc10.8, the nonmagnetic layer has an average thickness of not more than 1.1 m, and the nonmagnetic powder has an average particle volume of not more than 2.010.sup.5 m.sup.3.

A magnetic recording medium is provided and 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 of the magnetic recording medium is 3.5 mt.sub.T5.3 m, a dimensional variation w in a width direction of the magnetic recording medium to tension change in a longitudinal direction of the magnetic recording medium is 700 ppm/Nw2000 ppm/N, and an average thickness t.sub.n of the non-magnetic layer is t.sub.n1.0 m.

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.

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.

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.

A magnetic recording medium includes a substrate, an underlayer formed on the substrate, and a magnetic layer formed on the underlayer. The magnetic layer includes an alloy having a L1.sub.0 structure. The underlayer includes a first underlayer and a second underlayer. The first underlayer includes Mo and Ru, the content of Ru in the first underlayer is in a range of 5 atom % to 30 atom %, and the second underlayer includes a material having a body-centered cubic (BCC) structure. The second underlayer is formed between the first underlayer and the substrate.

A magnetic recording medium includes a non-magnetic substrate, a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic layer, and a protective layer arranged in this order. The perpendicular magnetic layer includes a first magnetic layer and a second magnetic layer from the non-magnetic substrate side in this order. The second magnetic layer contains a magnetic grain and provided farthest from the non-magnetic substrate. The first magnetic layer has a granular structure that contains an oxide in a grain boundary. The second magnetic layer has a granular structure that contains a nitride of an element contained in the magnetic grain in a grain boundary.

A magnetic recording medium includes a non-magnetic substrate, a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic layer, and a protective layer arranged in this order. The perpendicular magnetic layer includes a first magnetic layer and a second magnetic layer from the non-magnetic substrate side in this order. The second magnetic layer contains a magnetic grain and provided farthest from the non-magnetic substrate. The first magnetic layer has a granular structure that contains an oxide in a grain boundary. The second magnetic layer has a granular structure that contains a nitride of an element contained in the magnetic grain in a grain boundary.