Sony Corporation

Sony Group Corporation

Takashi Kataguchi

Takeshi Takahashi

Natsuki Ichise

Masaru Terakawa

Katsunori Maeshima

Minoru Yamaga

Tomoe Sato

A magnetic recording medium is a tape-shaped magnetic recording medium that has a recording layer including an ε-iron oxide particle. An area ratio R(=(S/S)×100) of a total area Sof an SFD curve of the recording layer in a perpendicular direction and an area Sof the SFD curve in which a coercivity Hc is in a range from −500 [Oe]≤Hc≤500 [Oe] is equal to or less than 5.5%.

Magnetic recording medium

The present disclosure provides where a magnetic recording medium is provided and includes a base; an underlayer that is provided over the base and includes a non-magnetic powder; and a magnetic layer that is provided over the underlayer and includes a magnetic powder and a binder, wherein an average particle volume V of the magnetic powder is 1600 nmor less, an average thickness of the magnetic recording medium is 5.3 &#x3bc;m or less, a thermal stability KV/kT of the magnetic recording medium is 63 or more, and a ratio Hrp/Hc1 of a residual coercive force Hrp of the magnetic recording medium measured using a pulsed magnetic field in a perpendicular direction to a coercive force Hc1 of the magnetic recording medium in the perpendicular direction is 1.98 or less.

A cobalt ferrite magnetic powder includes magnetic particles that have a uniaxial crystal magnetic anisotropy and contain cobalt ferrite. A peak top 2&#x3b8; of a (3, 1, 1) plane determined by powder X-ray diffractometry using a CoK&#x3b1; ray is 41.3&#xb0; or more and 41.5&#xb0; or less. Some Cos contained in the magnetic particles are substituted with at least one selected from the group consisting of Zn, Ge, and a transition metal element other than Fe.

Cobalt ferrite magnetic powder, method of producing the same, and magnetic recording medium

The present disclosure provides a tape-shaped magnetic recording medium, including: a base; and a magnetic layer that is provided on the base and contains a magnetic powder, in which an average particle volume V of the magnetic powder is 2,000 nmor less, an average thickness of the magnetic recording medium is 5.3 &#x3bc;m or less, a thermal stability KV/kT of the magnetic recording medium is 60 or more, and a ratio Hrp/Hc1 of a residual coercive force Hrp of the magnetic recording medium measured using a pulsed magnetic field to a coercive force Hc1 of the magnetic recording medium in a perpendicular direction is 2.10 or less.

Growing community of inventors

Tokyo, Japan

Takashi Kataguchi