Magnetic recording medium, magnetic recording/reproducing device, and magnetic recording medium cartridge

A magnetic recording/reproducing device comprising:

• a feeding unit that can sequentially feed out a tape-shaped magnetic recording medium;
• a winding unit that can wind up the magnetic recording medium fed out from the feeding unit;
• and
• a magnetic head that can write information on the magnetic recording medium and can read out information from the magnetic recording medium while being in contact with the magnetic recording medium traveling from the feeding unit toward the winding unit, wherein
• the magnetic recording medium includes:
• a substrate;
• a base layer disposed on the substrate;
• a magnetic layer disposed on the base layer;
• and
• a back layer disposed on a side of the substrate opposite to the base layer,
• the substrate includes a polyester as a main component,
• a surface of the back layer opposite to the substrate has a kurtosis of 2.0 or more,
• on a surface of the magnetic layer, recesses having a depth of 20% or more of the average thickness of the magnetic layer are formed at a ratio of 10 or more and 200 or less per 1600 μm2,
• a surface of the magnetic layer has arithmetic average roughness Ra of 2.5 nm or less,
• the base layer and the magnetic layer each include a lubricant,
• the entire magnetic recording medium has a BET specific surface area of 3.5 m2/g or more in a state where the lubricant has been removed from the magnetic recording medium and the magnetic recording medium has been dried,
• a squareness ratio in a perpendicular direction is 65% or more,
• the magnetic layer has an average thickness of 90 nm or less, and
• the magnetic recording medium has an average thickness of 5.6 μm or less.

A magnetic recording medium cartridge comprising:

• a tape-shaped magnetic recording medium;
• and
• a casing that houses the magnetic recording medium, wherein
• the magnetic recording medium includes:
• a substrate;
• a base layer disposed on the substrate;
• a magnetic layer disposed on the base layer;
• and
• a back layer disposed on a side of the substrate opposite to the base layer,
• the substrate includes a polyester as a main component,
• a surface of the back layer opposite to the substrate has a kurtosis of 2.0 or more,
• on a surface of the magnetic layer, recesses having a depth of 20% or more of the average thickness of the magnetic layer are formed at a ratio of 10 or more and 200 or less per 1600 μm2,
• a surface of the magnetic layer has arithmetic average roughness Ra of 2.5 nm or less,
• the base layer and the magnetic layer each include a lubricant,
• the entire magnetic recording medium has a BET specific surface area of 3.5 m2/g or more in a state where the lubricant has been removed from the magnetic recording medium and the magnetic recording medium has been dried,
• a squareness ratio in a perpendicular direction is 65% or more,
• the magnetic layer has an average thickness of 90 nm or less, and
• the magnetic recording medium has an average thickness of 5.6 μm or less.