Magnetic recording medium having a dimensional variation
摘要
說明書
First, a magnetic field of ?1193 kA/m (15 kOe) is applied to the entire magnetic recording medium 10 (measurement sample), and the magnetic field is returned to zero to provide a remanent magnetization state. Thereafter, a magnetic field that is equivalent to the value of the remanent coercive force Hr obtained from the DCD curve is applied in the opposite direction. The magnetization amount is continuously measured at regular time intervals for 1000 seconds with the magnetic field applied. The magnetic viscosity coefficient S is calculated by checking the thus obtained relation between the time t and the magnetization amount M(t) from the following formula. M(t)=M0+S×ln(t) (M(t): magnetization amount at time t, M0: initial magnetization amount, S: magnetic viscosity coefficient, ln(t): natural logarithm of time) (Arithmetic Mean Roughness Ra)
The arithmetic mean roughness Ra of the magnetic surface is preferably 2.5 nm or less, more preferably 2.0 nm or less. When Ra is 2.5 nm or less, a better SNR can be obtained.
The arithmetic mean roughness Ra mentioned above is determined as follows. First, the surface on the side with the recording layer 13 provided is observed with the use of an atomic force microscope (AFM) (manufactured by Bruker, Dimension Icon), thereby acquiring a cross-sectional profile. Next, the arithmetic mean roughness Ra is determined from the obtained cross-sectional profile in accordance with JIS B 0601: 2001.
[Method for Producing Magnetic Recording Medium]
