Tape-shaped magnetic recording medium including magnetic layer having recesses on a surface, 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 tape-shaped magnetic recording medium fed out from the feeding unit;
• and
• a magnetic head that can write information on the tape-shaped magnetic recording medium and can read out information from the tape-shaped magnetic recording medium while being in contact with the tape-shaped magnetic recording medium traveling from the feeding unit toward the winding unit, wherein
• the tape-shaped magnetic recording medium includes:
• a substrate;
• a base layer disposed on the substrate;
• and
• a magnetic layer disposed on the base layer,
• 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 20 or more and 200 or less per 1600 μm2,
• on the surface of the magnetic layer, a logarithmic decay rate determined by a pendulum viscoelasticity test at a temperature of 10° C. or higher and 45° C. or lower is 0.025 or more and 0.035 or less,
• a difference between a maximum value of the logarithmic decay rate and a minimum value of the logarithmic decay rate is 0 or more and 0.020 or less,
• a squareness ratio of the tape-shaped magnetic recording medium in a perpendicular direction is 65% or more,
• the magnetic layer has an average thickness of 80 nm or less, and
• the tape-shaped 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 tape-shaped magnetic recording medium, wherein
• the tape-shaped magnetic recording medium includes:
• a substrate;
• a base layer disposed on the substrate;
• and
• a magnetic layer disposed on the base layer, in which
• 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 20 or more and 200 or less per 1600 μm2,
• on the surface of the magnetic layer, a logarithmic decay rate determined by a pendulum viscoelasticity test at a temperature of 10° C. or higher and 45° C. or lower is 0.025 or more and 0.035 or less,
• a difference between a maximum value of the logarithmic decay rate and a minimum value of the logarithmic decay rate is 0 or more and 0.020 or less,
• a squareness ratio of the tape-shaped magnetic recording medium in a perpendicular direction is 65% or more,
• the magnetic layer has an average thickness of 80 nm or less, and
• the tape-shaped magnetic recording medium has an average thickness of 5.6 μm or less.