High density magnetic recording medium for heat-assisted magnetic storage apparatus

A magnetic storage apparatus comprising:

• a magnetic recording medium;
• a magnetic head configured to write information to and read information from the magnetic recording medium;
• and
• a casing configured to accommodate the magnetic recording medium and the magnetic head,
• wherein the magnetic head includes a laser light generator configured to generate laser light, a waveguide configured to guide the laser light to a tip end of the magnetic head, and a near-field light generator configured to generate near-field light that heats the magnetic recording medium,
• wherein the magnetic recording medium includes a substrate, an underlayer, and a magnetic layer that are arranged in this order,
• wherein the magnetic layer has a granular structure including magnetic grains having a L10 crystal structure, and grain boundary parts having a volume fraction in a range of 25 volume % to 50 volume %,
• wherein the magnetic grains have a c-axis orientation with respect to the substrate, and
• wherein the grain boundary parts include a material having a lattice constant in a range of 0.30 nm to 0.36 nm, or in a range of 0.60 nm to 0.72 nm.